I also noticed the bolts rubbing on the top of the tank. (And the bottom of the seat itself is wearing on the little back protrusion that the fuel vapor tube connects to.) I found an easy fix though. The reason it's all rubbing is because none of the round back rubber stoppers on the bottom of the seat are making contact with anything. If you move the two stoppers that are near the back, from the holes they come in, to the set of holes a few inches farther back, they'll rest on top of the flat part of the latch assembly. It's really easy. Just give 'em a pull from one side and they'll pop right out. (There's no way to make the front stoppers rest on anything. They'd have to be made quite a bit thicker.)
After doing this, I found I had to apply a little pressure on the back end of the seat while latching it. But other than that, it's perfect. What little wiggle there was in the seat is gone, and no more bolts wearing on the tank top.
If anyone from Carter is reading this (or if anyone has a contact there they could talk to) I'd highly suggest moving the back stoppers as described by default.