ok u seem to me to want to dismiss reads,stacks,tempo and the game flow at the time and get jiggy with AKs but then fold to a 4bet?
I dont doubt your reads on this player pre were pretty much spot on, if you suspect someone to folding AQ or medium pairs to a active 3bettor then when they are 30bb effective i"d anticipate them to tighten up before raising again with u behind to act. Now in your situation the a 20bb limper uttg1 is raised by Mrs Tight [which to me narrows her range moreso than if it had been a open raise]
So what range do we put her on? TT JJ QQ KK AA AK AQ ?? agree/disagree ??
There is 18300 in the pot and the action is on u , if u choose to 3bet u think she would fold TT JJ AQ [24combo"s] and her 4bet range is QQ KK AK [21 combo"s]
AdKd - 42% equity
QQ+,AcKc,AhKh,AsKs,AcKh,AcKs,AhKc,AhKs,AsKc,AsKh - 58.096%
So why Dan if u had thought pre-flop how she reacts with her range before u acted, why risk 27000 [ish as u say] to win 18000
she is only folding to a 3bet 55% of the time , hence the ""theres loads of Fold equity malarkey"" , there is not enough FE to make this profitable... Something when especially live that u could of figured out beforehand imho...
edit - also it gets interesting if u thought about what range the limper has given your read preflop as possibly strong , then what did u plan to do after 3betting if the limper pushed and Mrs Tight called into your thinking preflop...