or... run out to the local hobby/model store, they sell a spray tint for lexan bodies for r/c cars. very good stuff, its built to be banged around on those trucks, ive got some around somewhere (from back in the day of my r/c's)
just get the spray tint, do 2-3 coats and then clear coat it same companies paints.
would be cheaper then the nightshade stuff.