Swung through there last summer on the way home from the Maine Mini Rally. The US side is unfortunately an artifact of a bygone era - ie, a dump. You can easily be off in the hood a few blocks from downtown.

We stayed at AAA Royale, which is between NF and Buffalo, and it was ok for a night or 2. It is a motel / RV park with blacktop pads. They gave me 2 slots to park in which was plenty roomy. About a 15 minute drive to the falls from there.

I think there is plenty of opportunity to park the bus near the falls in town. I would probably avoid Goat Island if memory serves me correctly. It gets pretty crowded and if you are still apprehensive manuevering your bus it may raise your BP.