Alright, I have gotten under my Globe Trotter for the first time. I was looking at what I think you all call 'banana strips', those blue and aluminum strips that cover the rivets for the belly pan. What I see is a ton of very nicely done rivets. I know I could drill them out and completely remove the belly pan. Not sure I do want to take the shell off completely now. I am working by the side of my house on a gravel bed with not much room to move and I have an idea I wanted to pass by you all for advice.
I do want to get whatever is under there cleaned out, also remove the floors and attend to any welding. What if I cut the belly pan underneath where the red line is....

Then do the same from the wheel well to the front. Then cut out the floors above, address any welding issues being sure to protect any aluminum around the edges. Put in new tanks and piece in the new ply wood. Then make strips to repair the cuts in the belly pan to rivet back together later. I think it can be done. Does that sound simplistic to those of you who have walked this road? Does my overall plan seem to make sense?
Thanks - Ken