Harbor Freight 500lb. cargo carrier for a spare tire?

Thanks for all your helpful replies! My plan to carry a not-mounted spare is due to the fact that I doubt at age 80 I'd be able to change the thing myself. Any decent road service should be able to change the tire (he hopes) ...but if not, at least I won't have to wait several days for a replacement. I have all the nec. hitch components and my B+ bumper is not the sewer storage type, so those adapters, etc. will not help. Next stop is Harbor Freight to check out their variety.