I have been thinking about an inexpensive way to haul a second spare tire when I know there will be sharp rocks with a higher likelihood of flats. This may also work as a temporary way to carry the primary spare tire.
This is the recipe I am contemplating: Take a folding 2" hitch adapter, insert a 2" hitch extender, weld a mounting plate for the spare to the top of the extender. When you want to access the rear doors, simply take out the pin from the folding hitch adapter, and the spare tire and hitch extender will fold down and lay flat, allowing you to access the rear doors.
Image of folding hitch adapter:
https://www.ebay.com/i/202540388315?chn=ps