Please keep us posted on the repair, and more importantly - the source of the leak.
I have finished the rot repairs on my Bigfoot. I updated my webpage with the details:- http://user.dccnet.com/radaniel/
I regards to the cause of the ROT
I could not find a "smoking gun" where the moisture got in
Because Bigfoot on the 2004 1500 series has an unprotected (i.e. not coated for rot protection) wood floor stringer at the rear adjacent to the approx 1" drainage trough at the lower rear of the camper (it where the two drain holes are at each rear corner of the shell are) any moisture whether from a leak or condensation will soak into the wood & migrate through the wood & eventually rot.
Due to the location of the rot in my Bigfoot, it could be a leak in the:-
1) Door frame & sill plate
2) The propane tank compartment
3) The water heater outer frame area
4) The window frame just above the water heater
4) The bottom access panel. I noticed that it was not sealed & when I had it off to do some floor rot repair near the lower door frame area there was some moisture there from a rainfall the previous night. I had the entrance door covered with plastic during the rainfall, so it was not from that area. I think the water went down the outer fiberglass wall & then around the curved bottom corner where it could soak into the wood frame.
5) The joint where the upper & lower camper shells meet.
I would suggest you focus on those areas & also go over all sealed areas, including the roof openings, use lap sealant for the roof.
Also when in storage have some kind of Dehumidifier to help prevent condensation. Where you live & how you store your camper determines what size or type of Dehumidifier. I live on the West Coast of Canada (rainy) & store my Bigfoot outside.
Bigfoot as well as other manufacturer's to keep costs down do not seem to spend the time to seal critical areas or provide rot proof materials, in my opinion.