If you have some carpentry skills you should not have a problem. When I replaced panels on my previous rv I used a combination of glue (like liquid nails) and screws. Since you have wood studs, paneling type nails in non obvious places should work to hold panel in place until the glue sets up. Also, if there is any signs of mold make sure you treat it with some type of mold eliminator. If the stud is soft, make sure you let them dry out and use some type of rotted wood restorer. Here's one example http://www.amazon.com/Bondo-20131-Ro.../dp/B00D5ZT6NO
Most importantly, make sure everything is dry and all mold is removed before closing it back up.