Interesting spot from an $8.80 500 cap tournament on Stars. Unfortunately PT4 wasn't working today so I had no stats, although my read was that no one had 3b me yet at this table, everyone playing pretty straightforwardly. 

The 3b is pretty small so I elect to flat. Is this a mistake OOP? My intention was to float a lot of flops and make a play if he showed weakness on the turn, but do I need to make this sort of play at this level? That is exactly what happens as he checks back turn so I decide to follow through with my plan and make a play at this pot. I decided to shove as I wanted to get the maximum fold equity. It's unlikely he has mid- or higher pocket pairs after checking back the turn so I wonder if I can bet smaller and get him to fold all of his air, like maybe just 7,000 as I don't feel comfortable check/calling this river. Also, this still leaves me with 11k rather than out of the tournament when it goes wrong. Do I get any more folds by shoving river rather than making a more value betting size? It seems like he only ever calls with a Qx hand, so it doesn't matter whether I bet small or jam, it gets the same amount of calls.

Poker Stars $8.00+$0.80 No Limit Hold'em Tournament – t350/t700 Blinds + t85 – 9 players – View hand 2164629
TournamentPokerEdge.com Hand History Converter

SB: BB = 6.8, t4770
BB: BB = 40.3, t28219
UTG: BB = 36.9, t25851
UTG+1: BB = 85.7, t60018
UTG+2: BB = 19.9, t13932
Hero (MP1): BB = 37.6, t26300
MP2: BB = 12.9, t9034
CO: BB = 61.2, t42860
BTN: BB = 23.3, t16279

Pre Flop: (t1815) Hero is MP1 with 7 A
3 folds, Hero raises to t1581, 1 fold, CO raises to t3150, 3 folds, Hero calls t1569

Flop: (t8115) 2 4 6 (2 players)
Hero checks, CO bets t4200, Hero calls t4200

Turn: (t16515) 8 (2 players)
Hero checks, CO checks

River: (t16515) Q (2 players)
Hero bets t18865 all in, CO calls t18865