After 50 hands, villain is running 25/19. No other reads.
He snap called the flop, then called the turn after about 3 seconds.

BTN is slightly loose and folds too often to cbets.

I just can't see villain having a good enough hand here to call.

Am I repping too small of a range on the river?

$3/$6 No Limit Holdem
5 players
Converted at weaktight.com

Stacks:
UTG ($668.00)
Hero ($618.95)
BTN ($665.45)
SB ($612.00)
BB ($600.00)

Pre-flop: ($9, 5 players) Hero is CO
UTG calls $6, Hero bets $27, BTN calls $27, 2 folds, UTG calls $21

Flop: ($90, 3 players)
UTG checks, Hero bets $62, BTN folds, UTG calls $62

Turn: ($214, 2 players)
UTG checks, Hero bets $156, UTG calls $156

River: ($526, 2 players)
UTG checks, Hero goes all-in $373.95