You do not want to put "unnatural" stresses on that long body. There are welded joints that might break/crack. i dimly recall that they are at the rear top of the door opening.
There have been posts/discussion on this topic. I am now travelling, and searching on a phone is not easy. If no one posts information, I will look tomorrow.
I dimly recall that we made a wood-frame, and then used two 4x4 or 6x6 cross-bars to lift up the frame and then roll the chassis out.
We needed a lot if space.
