Mondo
Have you considered hot dip galv. I towed mine up to Townsville under permit. I reakon its great, no paint chipping to worry about, especially were we live. Cost me $800 back in 08 but it goes on the weight of trailer.
Sorry i just had a thought, with you camper build you already have the floor in your trailer. Hot dipping doesnt like large flat areas such as floors. I left my floor out , had it dipped, then Sikaflexed a galv sheet in.
Regards Angus.