Just saw your post. I bought a used 2010 X-Lite 26bhxl from a friend in the spring of 2014. While looking it over, he showed me the repair bills where the dealer replaced the entire floor with 5/8" t&g plywood. The trailer never had water damage but the light-weight flooring flexed too much to his liking so he had the dealer replace it all. The labour came to 35 hours @ $85.00/hour. They used 6 sheets of plywood and some misc items (tapes, trims, etc...) as well.
I know it must be very frustrating. Keep after your dealer as they knew about this problem during the sale so you may have some legal recourse, if it comes to that. Also, check with Forest River as one of the other posters noted and see if they'll help and DOCUMENT EVERYTHING - phone calls included!!! Unfortunately, it takes a squeaky wheel to get the grease so don't let up!!!
By the way, we've used ours for two summers now and love it.
In the meanwhile, I have most of the original owner's manuals if you're missing any.
This is a great forum for help and advice so don't be afraid to ask. Keep us in the loop as to how you make out.
2010 Wildwood XLite 26BHXL