[georgezink]

You should be able to fix the leaks from the outside without removing the interior walls unless you just want to remove the walls. Replace gaskets on windows and doors and vent stack, replace caulk around the windows & doors with Vulcum, use par bond in all the seams, clean and caulk (Vulcum) around all lights. Check for any openings in the wheel wells. I would be very careful when replacing interior walls. They are attached to the ribs with rivets and add to the strength of the monocock construction of the trailer. I believe rivets are your best option.