floor experts?

unfortunately gdetrailer has no idea what he's talking about or is confused.  "Lite" trailers with bonded floor construction don't use wood joists or staples (you can't staple luan to foam), they all use aluminum joists which are basically a thin hollow wall joist that is crap.  The whole floor structure is bonded at the factory in a grid fashion and is 1/8 or even 1/16 luan on both sides, with a foam middle.  There is really no way to repair it because there is no structure to tie into, unless you consider a hollow mickey mouse aluminum frame to be sufficient. And you can't lay out or repair osb or plywood in just one area without doing the whole trailer, because you have a 1/8 top layer or less before you are at foam.   In very few cases you can inject epoxy into the floor IF the repaired soft area is very small.  It's also important to realize that sometimes soft floors are mistakenly assumed to be water damage, when sometimes it's simply an issue of little or no support underneath because part of the reason these are "lite" is because manufacturers save weight by placing support beams way too far apart, sometimes 4 feet or more under the trailer.  It's a terrible design and I would avoid any trailer with this construction.  My advice comes from rehabbing and flipping over 200 trailers in 18 years, so I'm well versed in their construction.  good luck