I think there's value in playing some speculative hands too. If your image becomes that of a nit then the maniac is just gonna fold as soon as you play back at him.
Playing vs maniacs can be really frustrating, but should be profitable in the long run. really pay attention to their ranges and don't be afraid to get it in if you're fairly sure you're ahead.
I think, never be afraid of them, because sooner or later, you can catch them on a bluff. After all, if anyone ever play with them and caught bluffing everyone else will see, with what cards came maniac. Good luck and come to you. Listen to your intuition
I've run across a few of those guys on ACR. Only play is all in. I make notes of the player and just wait for a hand, knowing I'm going to have to be all in.
Maybe don't do a full buy in, in case you need to rebuy and recoup a loss.