Is the floor sheet metal or wood? Ours was sheet metal and had no rust whatsoever so we kept it. Put on foam underlayment/vapor barrier and then luan with stick on tiles for part and cheap laminate maple flooring for the other part.
My build thread:http://www.skoolie.net/forums/f11/build-thread-for-haulin-oats-and-goats-11237.html#post113500
A gal, a guy, three cats, two dogs, one rabbit, and one goat, traveling the country together.