rust in campers

hey guys

more box trailer questions
just want to know if people had problems with rust in their camper trailers,
especially the the ones that are just painted steel.
because im still trying to work out if it worth spending the money and work involed to get my box trailer that im converting into a camper, hot gal dipped,(im now aware that flat panels will buckle under the heat) though i suppose if its sealed properly and looked after well rust may not be a problem in a just painted trailer.
it will very very rarely see the beach or salt water,lucky to be once a year, it will spend most time in national parks and caravan parks.oh! and the backyard..

thanks guys
all help appreciated

Cheers
Brentos