Actually the frame provides the strength and is stiffened a little by the shell. The interior fiberglass does some stiffening, but to a large extent the shell is just along for the ride.
If the frame and
axle are OK then it would be most probably OK to tow. I would cover the open areas and perhaps tape it with gaffer tape to hold the pieces together.
If it is an insurance repair job that is one thing and perhaps
Casita can fix it, but that could easily be more than the insurance company would pay (assuming your insurance company).
If the person causing the accident can be found and is known and ID as the cause then their insurance should make you whole with either a check to replace or pay for a proper repair.
A shop that repairs boats or Corvettes might be able to do the job, but either way it would be expensive.
Almost always the cost ends up with a DIY repair or totaled and someone else does the DIY I would guess.
Today an hour of someone's time is pretty high and there would be a lot of work for extensive damage repair and
painting or gel coat.
Pictures would be necessary to determine to any real extent.