A not-really-vintage but not far off rebuild of a Mallard

Cool project!
Yeah, when you get everything stripped out, the framing shrinks in importance. I can see where your water intrusion is and mine was about the same, roof-to-sidewall and in the corners.

I think you have a good handle on the project, keeping the drains in near to their current location bespeaks that. Moving waste tanks is a big deal.

I'll be following along on this one. Will you have to strengthen the floor to haul your toys in the back?