Howdy and Welcome to iRV2.com.
A few years back my friend told me that the floor on the 99 Bayside we sold him was doing the same thing. It took a lot of work to tear the old floor out but we cut it and pulled it out. we used treated plywood to replace the floor and even painted the bottom to help. It can be done, so take your time.
Jim (SSG US Army Ret.) and Cheri (TSG Phx ANG Ret.) Mesa, AZ
2006 Dodge Ram 2500 HD Mega Cab Diesel | 2005 Honda Goldwing | 2006 35' Dune Chaser 5th Wheel