Not sure exactly what you've still got in there holding it, but. . .
I had the floor and belly pan off of my Caravanner and towed it slowly (25 mph) to and from the welder who was 8 or 10 miles away. For sure you've got to have something holding your shell up, something has to replace the floor between the C channel or J channel or whatever you have and the outriggers.
In my case, I cut strips of 3/4" plywood about 6" wide by 18" long and put them on top of the outriggers and under the C channel. They were held on by C clamps. So, my shell was held on by its weight on top of the outriggers and by the steel plate riveted onto the shell at the forward end.
I wouldn't want to go very far this way and certainly wouldn't want to go at all fast, but I'm sure we were fine doing it the way we did. Others may disagree.
And, welcome to the forums. All the answers to your questions will be here.