ryan, i have done lots of rattlecan work and i wil l say i have not been happy with krylon fusion paints.. they never seem to set right for me. even after curing for a week, 10 seconds with a rubbing compound by hand took it completely off.

i would say a plastic primer and then a high good quality paint and clear

i agree with wormgod on the duplicolor recommendation. ive been using their perfect match paints recently and you can get a really nice finish out of those, and had no problems with them.. also i did my engine cover with rustoleum rust-tough and it turned out great, and no problems with the heat at all