Sorry about the structure of the post, not sure about how to post HH properly so i'll do it manually for now...

Blinds 800/1600/200a, around 12000 remain from the 63000 that started and I am around 1.5x average stack at this point

SB: (16119 in chips)
BB: (74792 in chips)
UTG: (86449 in chips)
UTG1:(120709 in chips)
UTG2: (71908 in chips) (HERO)
LJ: (28354 in chips                                                                                                                       

HJ: (46614 in chips)                                                                                                                   

CO: (61919 in chips)                                                                                                                    

BN: (72569 in chips)

X: posts small blind 800
Y: posts big blind 1600
*** HOLE CARDS ***
Dealt to HERO [Ac Kc]
UTG: folds
UTG1: folds
UTG2: raises 1600 to 3200 (HERO)
LJ: folds
HJ: folds
CO: folds                                                                                                                                    

BN: Raises 4800 to 8000 

SB: raises 7919 to 15919 and is all-in

BB: folds

I have been opening plenty of pots and have somewhat of a loose image...My read on the 3bettor is that he is playing a loose aggressive style and that he will be 3betting me with a decent part of his range, especially given that I have been opening a decent amount, particularly in the last orbit or 2...Reads on the 4bettor are limited, they have been playing tight over a 30 hand sample since joining the table but this may just be down to being handcuffed by stack size....

Edit: I have opened and showdown hands like ATo and 89s after opening from MP in the last 3 orbits...

3bettor: Given the above and my perception of them, I gave him a range of something like                   88+, ATs+, AJo+, KQo, KJs + a number of lighter 3bets, i.e hands like 44 or 68s attempting to grab the initiative in position

4bettor:Been very tight over 30hands, but joined the table with around 12bb's so not much to go on...I have assigned them a range given both mine and the 3bettors image of 99+ AJs+ AQo

Options: 

Fold: seems way too nitty and weak vs the perceived ranges of my opponents...however, it has the benefit of preserving my solid stack and position in the tourney 

Call, knowing that the BN will at least call behind, meaning that I have to play an inflated pot OOP vs and aggressive opponent...not a great spot

5bet to around 28/30K: Has the benefit of looking stronger than moving AI? Probably narrow the BN range to pretty much the same as an AI, but how can I then react if BN does shove? Do I have to sigh GII knowing I've probably got around 25-30% to scoop (33-40% to win the 111K side pot) as I am getting 3:1 on the call

Move AI to isolate the sb: I have 52% vs the sb's range and given that I can get the BN to fold around 75-80% of their range, (QQ+ call) I can be pretty sure this is +EV but is it optimal?

I have done some EV calculations and will post later when finished/after some feedback...