There's nothing very mysterious or even special about paint
What exactly is it you are painting
I'm under the impression that you're talking about cabinet doors, etc.
Is it anything more complicated than that?
Are yours surfaces that require some kind of specialized properties, or are you just trying to cosmetically rejuvenate the inside of the trailer?
Reid's is a good suggestion if you're trying to coat a surface that is exposed to specific extraordinary conditions; barring that circumstance, cosmetic paints differ very little except in price.