rubberized undercoating holds water in and causes more problems than you realize.
Oil it down with fluid film.
You will have rust down south ,you wil get it in areas you never dreamed of due to moisture creeping into places that are innacessable to painting equiptment from the assembly line ,
I has a Mote Carlo that developed rust in the roof pillars because the factory sprayer cant paint in there. The salt air in florida rusted it from the inside out
Unless you are in the southwest desert , you can expect rust, at some poin, in some places, eventually