Maureen:
You had some questions and we started running off at the mouth, for which I apologize. The least I can do is attempt to actually answer them in my trademarked cryptic style:
Original parts: No, and you won't need them, because all the appliances are generic RV parts. Only the
fiberglass hull and frame is original to
Burro. And with most trailers. A welder can do the frame, and a boat shop can do the
fiberglass. You are highly unlikely to get totally stuck on such a project.
Worth more original: Unlikely, but it depends on the buyer. Generally speaking these are not artifacts, so properly done modifications will probably just enhance the value.
Laminate floor: It has been done and to good effect., but check under the carpeting for how the inner shell fastenes to the floor. The transition, which is not level, may give you pause. I would never do it, because if moisture should come into the trailer through vents,
windows, whatever, you may not be aware of it until it is too late and the damage is extensive.
Weakness in floor: No experience with this, although your idea seems to have merit.
Water pump: I take it there is no shower, toilet, or hot water heater. A good hand pump should be just the ticket, and they are available from any RV parts supplier. As I stated, my personal opinion places no value on trying to stay original.