bellagio Cup ME, can I bluff on this river?

[PhatPots]

ME at Bellagio Cup, Hero is sitting with about 24,000 chips

Right now my image is pretty tagish

UTG is really big guy. Probably about 500 lbs (Not exaggerating here). He is pretty loose preflop and postflop.

UTG+1 is a middle aged guy, a thinking player who has been pretty aggressive, he is a bit laggy. He has played back at me a few times.

UTG has about 11,500 to start the hand
UTG+1 has just a little bit less than me, 22,000


blinds are 100/200

Preflop: Hero has A [img]/images/graemlins/heart.gif[/img] Q [img]/images/graemlins/heart.gif[/img] in the Sb
UTG calls, UTG+1 calls, MP1 calls, Mp2 calls, <font color="red"> Hero raises to 1,400</font>, BB folds, UTG calls, UTG+1 calls, Mp1 folds, Mp2 folds

Flop (3 players): 2 [img]/images/graemlins/spade.gif[/img] 5 [img]/images/graemlins/spade.gif[/img] 2 [img]/images/graemlins/heart.gif[/img]
<font color="red">Hero bets 2,500</font>, UTG calls, UTG+1 calls

Turn: 3 [img]/images/graemlins/club.gif[/img]
Hero checks, UTG checks, UTG+1 checks

River: K [img]/images/graemlins/heart.gif[/img]
<font color="red">Hero bets 5,000</font>


Comments please
When I bet 5,000 UTG has only 7,500 remaining.

What do you put on UTG+1 on with his call on the flop and check on the turn, besides him flopping a set of 5s? I would think he would bet the turn unless he has a flush draw.

I kept thinking I would be able to fold a smaller pair, because they had to put me on a bigger pair, or AK (because everyone always thinks it has to be AK).