Need to find the source, and stop the leak before you bother with any repair. Nothing worse than fixing something in dry conditions, only for it to happen again from the same problem.
Being a 5th wheel, it likely has a joist-floor, which can likely be repaired in the affected area. Those with ultralites (including laminated floors without joists) are much worse-off when soft spots surface. Ask me how I know.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller