I took the risk and bought a used Altima spare on eBay, knowing that it will be difficult to fit around my 2" Torklift Ecohitch. It should arrive in the next week or so. I removed the undertray and took some photos per TonyWilliams' now somewhat dated request.
Hitch looking rearward toward LH side
Clearance from floor to top of hitch crossbar
Rear of load floor to front of hitch
Undertray bracket to front of hitch
Based on the measurements, it looks like I will need to deflate the spare. This whole arrangement is far from ideal, so I'm willing to live with inflating with the standard air compressor — if it I can get it mounted. We've had three flats in 30k miles that required a trip to the tire shop. The first required a tow and the other two were close enough to home that I was able to get the car home and remove the wheel and take it to the shop. However, the most recent was at 5 p.m. on Dec 23, 2020, meaning that I couldn't find anyone to repair or replace the tire... and we were traveling the next day. Brutal. So, I want to have a backup option even if it's comparatively a hassle.