sry for the late reply, but i would practice using fleece (high in polyester) and then applying the resnin to that.
it is very popular especially with sound systems.
almost all of the really glossy sound systems now adays use this fleecing
but preactice on something other than the door panel
*note* you will need to be goo and patient with sanding in this. but again practice.
*painting wise get a nice auto paint and clearcoat it.
using the fleece especially has alot of strength. tho im not sure on the crash test ratings..
like i said, practice, and with that practice youll get an idea of how it looks.
i wish you luck, and cant wait to see what the result is in the future.