Jethro,

Forgive George , he has sinned.

And just to make you feel a bit better dissimilar metal's can be welded
together with no problem at all, and be as strong as welding the same
together.

If you have the right wire, or rod.
anything is possible.

High nickel content rod welds anything to anything.

Stainless can be and is as strong as mild steel.

It just depends on what alloy you have in it, that's all.

And the bigger alloy content, the more money your going to spend on it,
regardless if it's coming from Tiawan, Burma, Bangladesh, French Indo
China, or Hong Kong.

Your best bet would be using mild steel, and have the unit powder
coated.

One problem here.

I don't think I'd be hanging my scooter off the back of my Van.
Even if it's only 350 lbs. ( what bike weighs three and a half ? A YZ125
Yamaha? ) that's one heck of a load swinging out behind the bumper.