[tommygunne]

Ideally you want to get it all in the middle (obv.) but its clearly going to be difficult to do that.
It would help lots if you've an aggro image?
Or what sort of image has villain?
As chris says he's not going to bet the river with air(maybe) but will bet with some sort of hand.
If he has some sort of hand you are much better off trying to get more in now. i would be stuck between raising the flop or turn depending on villain.
A lot of hands may be willing to call bets and so inflate the pot for bigger bets on the turn or river, and I think that the implied odds if he has one of these make up for the lost bluffs if he has air.
Also there may be a lot of potential action killers on the turn or river.