Roger that. Lexan paint, underside only
Make sure you spray the underside of the body and not the exterior as well.
I use Pectra. most common lexan paint you will see.
Its also not a bad idea to add layer of black as a "wear" coat.
Dont forget to remove the "overspray film" once you are done painting and ready to apply decals/stickers.
I have been known to apply headlight/taillight decals and THEN realize I still have the overspray film on the body