I think your biggest mistake was playing the hand. If you know you have that maniac-ish player behind you, it's not a good enough hand OOP.
For the next streets, if he's a calling station like you say sure bet into him. If he's the kind of calling station that calls only if he has something, then that something is most likely to be an A or a 7, flush draw is in there too. Against that range your A8 doesn't look too good to keep hammering.
If he's the kind of calling station that would keep calling that with 99, sure fire away, and accept that you're bound to have more variation against those types...