Having one built now that will hold Honda Gen. and couple other items. I also have the spare tire mounted to my swing out back door. I don't want my carrier to stick out too far past my spare tire. So the tray will be 8" lower than the tire and just as wide as back door. So my generator will site to the right of tire
This will be made to slide into my receiver and i can swing it with my door ( with bar pinned to spare tire frame ) or by itself, to the left out of the way to get to the storage under bed.
There are lots of ideas here on this site, this is where i found mine and modified to what i wanted /needed
David Mona
and the Girls