If the Someweed 56 works good on your Start it will be fine on the Gemini.
If you have a rack on the top of your trailer, why not put the Gemini there.
If it hang over a little in the front and rear, than should not be a problem.
You can cartop it for sure. Just put some rack pads or foam insullation tubing with
carpet over then over your racks.
You might want to find some of the plastic edge protectors the truckers use under their cargo straps at the corners of the load. These (with a little padding under) should keep the rails of the Gemini in much better condition.
I do not know of any bags for the Gemini. Maybe a custom bag would be the best you
My Gemini came from Thailand by air with two wide bags over it. On on the front and one from the rear.
Some baggage handler/genius decided to put the Gemini and a couple of early Phantoms (one plain Phantom, one custom race version) on the bagge machines.
Svein missed his plane from LAX to Orlando because they had to take the baggage transport machine apart to extract the Gemmini which would not go around one of the corners.
Hope this helps,