Reading further on also pointed out to me that the shell structure itself is not very rigid.
And the inside cabinets & partitions add rigidity. Leads me to ask whether you intend to insulate. As urethane spray foam adds tremendous rigidity if done correctly. Referring to proper bracing especially of the roof. I am glad you are sharing your project as it really got me to re-think how to best restore these units. I have extensive knowledge with oem fiberglass boat manufacturing & outfitting their interiors. All the same issues except the are rolling around not floating around. Play safe & keep sharing , Al
I am glad you alerted me about towing up a steep incline problem. Getting 5" lift on a Scamp would be quite reasonable & would allow for larger dia wheels which is a major plus. If the rear of the Scamp is just the little steel bumper good chance it would still drag. I would bolt on a 1/4'' aluminium skid plate to prevent any sort of damage to the rear. Better safe than ouch !