Personally, I'm a bit wary of heat...I mean its probably fine, as long as its not too hot (don't know how hot 'too hot' is), but I don't see it worth the risk. After one has expended time, energy and resources extracting the mescaline, it seems a bit silly risking your yield at the last hurdle wanting to get dry crystals really quickly.

That's just me though, am probably being over cautious, but a heat mat and a fan seem to do the job just fine.