If you're going to use aerosol cans, make sure you spray the parts and then leave them for a good amount of time (I'd give it at least 2 weeks @25 degrees or so) before applying the resin on top. Reason being, aerosols use a lot of solvents that can take quite awhile to evaporate from the part. If you seal it in with resin before all the solvents are gone, you risk trapping them in the paint which will cause it to stay slightly soft and possibly wrinkle up. You could also use a high temperature paint and bake it in the oven, then you shouldn't need to leave it for as long. I'd probably still give it a good week though.
Is there a reason you don't want to use clear coat spray paint on top? It would be much easier and far less work, possibly giving you a better finish as well. Though does scratch quite easily unfortunately.