Depending on how much crack you've got in you when the LSD hits you (are we talking about a single hit, then taking a blotter? Or constantly re-dosing crack while you're tripping?) that sounds like a recipe for massive manic/paranoid/psychotic overstimulation.
Especially if they're strong blotters and you get trapped in a thought loop, forgetting that you just had your last puff 3 minutes ago.
High doses of stims and LSD are a pretty iffy combo to begin with, especially if they're as short-acting and compulsive as crack.
Also, I'm not sure I'd be thrilled about the idea of someone who's cracked out *and* tripping handling an open flame.