I have a Super Sherpa as well for the back of my RV. I'm on my second one, first was stolen.
I like it so much better than all the others mentioned here so far.
It's air cooled, has a carb, and can be worked on by just about anyone around the world.
It's fairly light at 280 pounds, has normal size tires that can be easily found.
I put a top box on mine and can go into town, get groceries, do laundry, etc.
Has rear passenger foot pegs and grab handles for 2 up riding.
I also have an extra front sprocket, one size up, for doing more highway riding.
The bike is geared pretty low stock, the 6 speed gearbox is nice.
It's damn near bulletproof, just what you need for exploring away from base.