Raf, this is why when I got into painting, I kind of learned to use all of one system of paint. All from one manufacturer. I have deviated slightly and with mixed results and disastrous results......test test test.
Some of that rattle can paint is pretty weak, and a strong clear will just melt it right off so be careful. So after these adhesion tests you will have to test the clear, and that can will be dead in hours if it is the 2 part clear
I hate cleaning guns as well so I know where your head is at. I think what you are doing_can_be done, just needs lost of testing and if possible buy all the paint from one manufacturer (one paint system)