The critical structure in a hunter trailer is the load-bearing divider walls between the forward cabin (where the dinette/bed is) and aft cabin (where the stove, sink, and fridge
or icebox) are. The stove/sink side also has an added inner fiberglass shell comprising the 3 side walls and overhead all in 1 piece
above the kitchen countertop, making a washable surface on that side. The other side doesn't have a separate divider wall, but the whole fridge
and closet cabinet is load bearing.
The previous owner of my Compact Jr. gutted it just like you want to do to yours. He kept the roof locked down and never raised it. I found out why the first time I raised the roof to assess the condition of the rotted canvass. The pressure of the raise mechanism on the 4 corners of the roof caused the roof opening lip to buckle an fold in on itself across the middle where the walls should have been.
Not pretty and very frightening to experience.
This is the same phenomenon that results from cutting the roof off of a coupe to create a convertible. The automaker has to beef up the framing under the doors to keep the car from folding itself in half, making a convertible significantly heavier than a coupe.
I had to have 2" x 1" x 9' steel "L" beams bolted to the outside along each side of the inner roof lip to support the thin fiberglass structure when the roof is raised. I used old warehouse shelving legs. they bolted to the opposite side of the lip from the roof raise mechanisms, tieing them together on each side bridging the weak center of the body. They did not show on the outside because the fabric sides covered them.