Rick, I'm having a little trouble visualizing your proposal. Some pictures or diagrams would be very helpful I think.
If you rotate the shell higher on one side without disconnecting the lift arms from the shell, you might twist the connected side, especially if it is still attached to the torsion bar.
When I tried raising the shell from underneath, it was extremely difficult to keep my 2x4 lift supports stable. and from tilting to one side or the other.
By doing this from inside, I was able to
- screw the supports into the dinette structure so they stayed in place
- place fore/aft angle bracing
- place side-to-side bracing, using 4 screws on each post to prevent any sideways swing.
- install my hydraulic jack so that I had just a short jacking post. This was much more stable than putting the hydraulic jack on the ground using a long jacking post.
- lock the centre support post to the 2 side posts with screws
Other thoughts:
My method would allow me to raise one side a couple of inches higher, but I would have wanted to have a similar jacking system on the rear. Perhaps using the interior method for the front where you have the dinette or sofa, and then raise the rear of the shell from the outside. The other shell will prevent the lifting shell from tipping sideways.
I had thought that if I had a large enough garage, I could make a pulley system and pull the roof off from above. That's how they do it at the factory.
If you release just the front lift arms, the rear of the shell will push into the roof of the other shell. You will need to raise the entire shell at least an inch or so to prevent this.
To lift the shell from outside, I would have needed longer 2x4's to lock them together. I would have needed to do something to prevent the base from kicking out