MP is 20/16 with a 4.0% 3-bet over 91 hands.
SB is 25/20 with a 9.7% 3-bet over 329 hands.

MP's 3-bet % is so low that I'd expect him to flat hands as strong as AKo/QQ here, in addition to all pocket pairs 22+ and maybe some suited hands since we're deep along with CO/BTN who might juice the pot if they also call. CO/BTN have a combined 3-bet % of 13.2% so it's not likely he'd get squeezed.

SB is at 100BB stacks and could easily squeeze us here with a polarized range. Instead he opts to flat so he's very likely to just be set mining.

We have a BDFD and MP can't really continue with his weaker pairs or floats here since SB can still C/R us. I expect MP's continuing range to be 33, 55, Axs incl. A3/A5, AQo+ and maybe TT-QQ or 22/44 which will peel 1 street with a gutshot. I never expect MP to raise a set here although it's possible he might put a small one in with A3/A5 since these hands are able to be counterfeited sometimes or with 22/44 as a semi-bluff.

SB folds so now we're OOP.

I'm a bit hesitant to fire a second barrel here despite picking up a flush draw.

TT-QQ are the only hands that fold to this turn bet and there are only 18 combos.

No other part of his range is folding:

A2s (3), A3s (2), A4s (2), A5s (2), A6s (3), A7s-AQs (18), AQo (12), AKo (12), 22 (6), 33 (3), 44 (3), 55 (3) = 69 combos

If I'm targeting the TT-QQ portion of his range, I should have bet something like $6. This would coincide perfectly with villain's MDF of roughly 80% and it would be giving myself the correct price for my draw (unless he raises, which he might not do with a large chunk of his weaker Axs). Although realistically for that price he still might not fold.

I want to target the weaker aces that called 2-barrels here. Obviously no boat or wheel is folding, but the good news is that A3s/A4s just got counterfeited and the 5 removes some sets from his range.

Targeted folding range: A3s (2), A4s (2), A6s-AQs (21), AQo (12) = 37 combos = 53.6% which is the amount of times my bluff needs to work.

To achieve this, I need to make a small overbet of roughly $63.

So my bet of $42.50 was a bit too small. With this bet size he needs to defend 56% of his range, which is 38 combos and allows him to add half his combos of AQo into the mix (probably those without the Qc).