Reverse implied odds calling the turn with AK?

[paperboyNC]

3/6 or 5/10 Hold 'em

I have AK and end up heads-up with a very aggressive player by 3-betting the flop. I'm on the button. MP2 raises to 2BB, I re-raise to 3BB. Everyone folds.

Flop is rags (four actual flops):
[6h 2h 8c]
[3c 5s 3h]
[2d 2c 3s]
[5c 6h 6s]

FLOP: Pot is 7.5SB. If he bets, I raise. If I bet, he raises.

TURN: Pot is 6BB. The turn is another blank. The villian bets into to me. I am getting 7 to 1 from the pot and am 6.7 to 1 to get my overpair. I call.

RIVER: Pot is 8BB. Even when I don't hit my ace or my king, I feel compelled to call another big bet on the river getting 9 to 1. I call.

Results

[6h 2h 8c] Beat 95: 8 BB (the 6BB in the pot + 2BB he bets)
[3c 5s 3h] Lose to AQ: 2 BB (I called twice) -- queen on the river
[2d 2c 3s] Lose to 88: 2 BB (I called twice)
[5c 6h 6s] Lose to QQ: 2 BB (I called twice)

Net Profit: 2BB

So it appears that I'm getting 4 to 1 from the pot and need to win only 1 in 5 hands to turn a profit. Should I ever consider folding the turn heads-up since I am always forced to call the river?