Hi all, with apologies for the late appearance of this blog.
The preamble:
26 (2 words), near 44 14 8, the brainchild of 3 1 Across, was SUPERFICIALLY intended to be a showcase for 20, 27, 25 and 22. Every clue except the first and last contains an extra word of at least four letters that must be removed before solving. In clue order, the first, third or fifth letters of these extra words (approx. equal numbers of each) identify the legend to be written under the grid. Chambers (2016) is recommended. 39 is in ODE. One answer is an abbreviation.
It didn’t take too long for some of the unclued entries to become apparent and from there the theme and the other entries, although I did look up the sculptor. The first sentence of the preamble is revealed to be:
MOUNT RUSHMORE [26], near KEYSTONE SOUTH DAKOTA [44 14 8], the brainchild of GUTZON BORGLUM [3 1 Across], was SUPERFICIALLY intended to be a showcase for GEORGE, THOMAS, THEODORE and ABRAHAM [20, 27, 25 and 22].
So far, so straightforward. However, it took me much longer to ferret out the message from the extra words in the clues even though, having read the Wikipedia article on Mount Rushmore, I could guess roughly the direction we were going. For some time I had pencilled in “tale” as the first word, which didn’t help. Not that kind of legend! The later longer words also proved elusive … but the message was there to be chiselled out:
NAME OF INDIAN BEING COMMEMORATED NEARBY
A memorial to CRAZY HORSE is under construction less than 20 miles away, and I was interested to read more about its history. Thanks Kruger!

CRAZY HORSE
| # | ANSWER | Clue with definition underlined | ||
| Explanation, with quoted indicators in italics and ANSWER letters in bold caps | ||||
| Across | ||||
| 6a | DAWDLE | Waste time returning a lot of money to Dubliners on a regular basis (6) | ||
| Backwards (returning) WAD (a lot of money) + every third letter of (… on a regular basis) to DubLinErs | ||||
| 11a | QUARE | To some [extent], quaint unopened cotton flower in Louisiana not special (5) | etn | N |
| [s]QUARE (unopened cotton flower in Louisiana), not S (special) | ||||
| 13a | FAIR | [Extraordinary] trade show to go on we hear (4) | eta | A |
| FARE (to go on), homophone (we hear) | ||||
| 15a | ENSA | Table stripped of mahogany [completely] at the front for wartime entertainers (4) | cml | M |
| [m]ENSA (table) stripped of M (Mahogany at the front) | ||||
| 17a | MEZZO | Starts to medicate each [large] zapped zit – only moderately (5) | lre | E |
| Initial letters of (starts to) Medicate Each Zapped Zit – Only | ||||
| 18a | NUMEROUS | Several [boozers] use no rum in a cocktail (8) | boe | O |
| USE NO RUM anagrammed (in a cocktail) | ||||
| 19a | AGIO | Movement of [foreign] stocks and shares since I invested (4) | fri | F |
| AGO (since) with I put inside (invested) | ||||
| 21a | SETAE | [Quickly] tease out bristles (5) | qik | I |
| TEASE anagrammed (out) | ||||
| 24a | EERY | Weird [nationalist] stronghold spoken about (4) | nto | N |
| Sounds like (… spoken about) EYRIE (stronghold) | ||||
| 30a | HELVE | Put aside [gadget’s] uncovered handle (5) | gde | D |
| sHELVEd (put aside) without outer letters (uncovered) | ||||
| 34a | À GOGO | Past [English] success in abundance (5, 2 words) | egi | I |
| AGO (past) + GO (success) | ||||
| 36a | SOHO | Large market for computer kit [arranged] in part of London (4) | arn | A |
| Two definitions | ||||
| 37a | RETAMAS | Prince taking back [fancy] holly plants (7) | fny | N |
| RAS (prince) having inserted (taking) in reverse (back) MATE (holly) | ||||
| 39a | ADORAL | River in central region of Colorado [basin] already indicative of where the mouth is (6) | bsn | B |
| R (river) in the middle of (central region of) ColorADO ALready | ||||
| 41a | ASTRONOMY | Old non-European [early] monastery involved in heavenly studies (9) | ery | E |
| O (old) and MONAST[e]RY without E (non-European …) anagrammed (involved) | ||||
| 42a | AMMO | Components of preposterous [forbidden] custom-made missiles perhaps (4) | fri | I |
| Part of (components of) custOM–MAde reversed (preposterous …) | ||||
| 43a | TEAR INTO | Furiously scold stationer badly neglecting [infant] son (8, 2 words) | ifn | N |
| An anagram of (… badly) [s]TATIONER neglecting S (son) | ||||
| 45a | CAIN | Jacket bearing [Garda’s] current tribute no longer used (4) | gra | G |
| CAN (jacket) containing (bearing) I (current) | ||||
| Down | ||||
| 1d | BISMAR | Rampant [Caledonian] kinsman to damage steelyard in Kirkwall (6) | cld | C |
| Rising (rampant) SIB (kinsman) + MAR (to damage) | ||||
| 2d | OBOE | Alumnus with extremely [curious] ornate instrument (4) | cro | O |
| OB (alumnus) + outer letters of (extremely) OrnatE | ||||
| 4d | LAHORE | City, say, to complain about old-fashioned [comprehensive] teaching? On the contrary (6) | cmr | M |
| AH (say, to complain) inside (about …? On the contrary) LORE (old-fashioned teaching) | ||||
| 5d | MENUS | Soldiers against [mostly] American lists of options (5) | msl | M |
| MEN (soldiers) + US (American) | ||||
| 6d | DISMAYS | A few weeks in [dreary] Norfolk town appals (7) | der | E |
| MAY (a few weeks) in DISS (Norfolk town) | ||||
| 7d | ALAE | Side petals rising in ideal [symmetrical] alignment (4) | sme | M |
| The answer is reversed inside (rising in) idEAL Alignment | ||||
| 9d | LIP | No [sports] clubs to embrace impudence (3) | sot | O |
| There is no C in (no clubs to) [c]LIP (embrace) | ||||
| 10d | ERASED | Removed [other] Times editor (6) | ohr | R |
| ERAS (times) + ED (aditor) | ||||
| 12d | RENDERED | With bombers finally departing, shaken [German] Dresdener submitted (8) | gra | A |
| Without S (with bomberS finally departing), an anagram of (shaken) DRE[s]DENER | ||||
| 16d | FREEMASONIC | Mistakenly enforce aims of secret [terrorist] organisation (11) | tro | T |
| An anagram of (mistakenly) ENFORCE AIMS | ||||
| 23d | AUTOTOMY | Car leads to tragedy of [entailing] my loss of body parts (8) | eti | E |
| AUTO (car) + initial letters of (leads to) Tragedy Of + MY | ||||
| 28d | KARNAK | Site of many ancient buildings of dubious rank on [distant] area adjoining Cambodia (6) | dsa | D |
| An anagram of (dubious) RANK + A (area) + K (Cambodia) | ||||
| 29d | NGAIOS | Marsh possibly beside last of [Nicaraguan] cypress trees (6) | ncr | N |
| NGAIO (Marsh possibly) beside the last of cypresS | ||||
| 31d | LISTEN | Silent [apprentice] struggling to follow advice (6) | ape | E |
| SILENT anagrammed (struggling) | ||||
| 32d | CORONA | A type of cigar responsible for 75% of thrombosis [deaths] (6) | dah | A |
| The answer is forming 75% of (responsible for 75% of) CORONAry (thrombosis) | ||||
| 33d | JOLYON | Name heartless [former] marine in advance (6) | fre | R |
| Without the middle letter (heartless) JOlLY (marine) + ON (in advance) | ||||
| 35d | TARA | Old reindeer overlooking northern [Alberta’s] dead bracken (4) | abr | B |
| TARA[n][d] (old reindeer) omitting (overlooking) N (northern) and D (dead) | ||||
| 38d | AS TO | Regarding air staff [always] heading in one direction (4,2 words) | awy | Y |
| AS (air staff) + TO (heading in one direction) | ||||
| 40d | EME | Whichever way you look at it, he’s your long-lost uncle (3) | ||
| A palindrome (whichever way you look at it) | ||||