One possiblity you might try... mouse traps. Put a sheet on the hood to protect your paint, folded a few times, then set the traps, but you're going to need to set them such that when the cat sets them off, it doesn't get his paw - it could break their toes, which is not what I'm suggesting. You only want to scare them. When those things go off, they make quite racket - they scare me when I'm setting them!
If you use a little ingenuity, you can set them face down. If set off, they will snap harmlessly, but they will make a racket and flip up in the air a bit, should anyway, and ought to do thr trick. If they are set off when you find them in the morning, do it again for several more night.
Now, the cats are not dumb, so they might learn it doesn't hurt them, but I'm thinking they probably won't chance it once they have the experience of setting one off.
Just don't sit them face up so they get hurt on the traps. Put a tiny piece of wood or something underneat one end so you can leave it set and face down. Something like that.
Maybe that will work.