Warren -
If the floor/subfloor is intact, I would not touch it. The plywood subfloor
is a crucial element of the entire 'monocoque' design; besides, any repairs
(plumbing, wiring, and especially frame problems) will be done from
underneath, anyway.
Instead, I would drop the rear belly pan for access to inspect for
frame/electrical issues. An added advantage to dropping the belly pan is
that it gives you an opportunity to practice working with panel sections and
rivet-removal and replacement in an area that is not visible - a great place
to do trial and error work.
Tuna
Reno, NV