DLR,
Here's an idea. Take the tire off along with the entire spare tire carrier. Replace the spare tire carrier bolts with the originals in their place to cover the bolt holes. Take the spare and lay it horizontally on the rear of the inside cargo deck. You can build a cargo shelf with either 'King Starboard' for the non-wood, low-maintenance deal or stained plywood for the low-cost deal. This way, you can fit a full size spare tire (there's 48 " between the wheel wells) and go vertical with storage. This will leave you with enough room on the sides for, let's say a hyd. jack in a .50 cal can as well as a tow strap and a modicum of tools. Vertically, you can go almost 27" off the floor until things go to the top of the rear seat. If you'd like pics, just reply "show me" and I'll get some of my cargo area storage solution off to you before the end of the day on Saturday.
All that said, all of our needs are different here. Some need their back seat for the kiddos, in-laws, etc. I don't and would sooner pull mine than drive anywhere without a usable spare. That day will be when Murphy's Law of Road Hazards come into play and I'm screwed. I appreciate your situation on the weight of the spare. I'm in your age group with two (2) torn rotator cuffs.
Ablediver been there. Ablediver speak truth.
Ablediver out