I wouldn't have thought that spray paint would hold up to being covered with a coat of resin. At least not the resin were talking about, maybe the resin used for crafts and table tops, which is of no use to us here. As you know, laminating or tooling resin, is not clear. I'm not sure how it'd look color wise over paint, if it could be done at all. Gel coat chemicaly bonds to resin, paint does not. You're interrupting the bond between the two by using the rattle can paint. Gel coat should, if applied correctly, last a life time.
A layer of cloth will do nothing, unless your're covering a wood deck boat. Unless you have your finish mirror smooth, it will show every bump, dip and any other imperfection there. The best thing for you to do is to lay down 1oz of mat with some cloth on that. The purpose of cloth over mat is to squegie out the air bubbles. Many high-end builders I was lucky enough to work for would squegie out the air bubbles during lamination, and then remove the cloth before the resin kicks to save on the weight of the hull. Very clean lay up. You still have a bunch of sanding to do to get to this point.

On the other hand, helmets are made of layer upon layer of cloth. Dick Schuster and Gil Gaska, before they started Tahiti, were laminators at Powercat and built some of the race boats out of nothing but cloth. Extremely strong hulls but very labor intensive as you can imagine. It would take 20 layers of cloth, at least, to do the job. This was in the late 50s and early 60s. Much has chnaged since then.
You can get very nice results by using a fine brush to apply the gel coat. It'll flow to a smooth finish...as smooth as being sprayed? No. But acceptable for most, we did it like that at most shops I ever worked at. Just mix it cool so it won't kick before it has a chance to flow.