Perhaps a frame with the tubing attached to match the grooves as you suggest.
Personally, I would build a vertical frame to match the handle height, in the centre of the cart.
Then attach the frame holding the tubes by way of pivoting on the vertical frame.
The reason I suggest this is that when you lift the front or rear of the AI to slide onto
your camper shell, you will be concentrating the weight in a small area. If the
tubes can pivot for loading/unloading, it will spread the weight and make sliding easier.
Something like this -

Just make sure the pivot point is past half way towards the rear. This will
mean there is more weight in front of the pivot so it doesn't tilt on its own.
I actually use 2x3" timber shaped to a V on top and covered in carpet.
I imagine the carpet makes sliding my TI easier.
Unlike most others, I leave the Amas attached when loading and unloading.
All depends on what you have available and how handy you are of course.
This is the rack I made. I use an electric winch to lift it off the car up to the ceiling.
To unload, I slide it off, put the frame attached to the rear, on the ground then
lift off the nose onto a cart. Opposite to load. The frame sits on roof racks to
transport.
This is my frame, which doesn't tilt and concentrates the weight when loading -

_________________
Cheers, Brian in South Australia
Tandem Island -
