I'm still fairly new to the rod game but paint I do know. If you prep your material good, and lay down your paint well, using quality materials, I cant imagine you would have any problems with it. Maybe if you left it in the sun it may fade over a really long time, but we're talking years in the sun, IF you use quality materials.
That being said i think I read on here or rodbuilder.org that someone used automotive paint and had it turn out great.