5/10 NLHE; 9-handed; effective stack ~4500
Straddle 20 is on
4 limpers, including BTN, SB folds
BB makes it 200
Folds around to BTN
What is BTN's calling (and 3bet) range ?

This could probably just be put into a solver (if I had one), to get the GTO solution.
However, since we have established that GTO ranges need to be adjusted to live games, I am interested in both GTO considerations and live play adjustments.
As for my reads on BB: he is a solid tight player. I assume his range here is quite skewed towards value; do not expect big bluffs on later streets either.

Well what's BTNs limping range? Assuming we have some fold equity we might raise something like 77+/ATo+/KJo+/suited Ax/K9s+/QTs+/J9s+/65s+ from BTN. Lets say we assess the SB as either tight or passive, and BB as tight, so the blinds aren't often raising and so we can usually go multiway with nut position if we overlimp. Therefore we can overlimp really wide. I probably overlimp something like 22-66, A5o->A9o, any two suited except maybe the absolute worst like 93s/62s etc., any two unsuited cards 9 or higher, K8o and 98o. How much of that wants to call a 10bb raise from a range that dominates us? We can't justify anything except baby pockets and arguably some suited gappers/Q9s. I'm probably folding 100% here, yes that's open to abuse but if this guy is only raising a tight range I don't care.

We don't need to limp-3bet ever in this situation but if we want some type of range specifically to counter attacks on a limp chain, we could do something starting with AKo plus suited Ax and some combos of AA and expand into suited connectors if we think we have good fold equity.