Like all of you, I wanted a full sized spare and preferably one with TPMS. So, what I did first was call Honda with the question about having a TPMS equipped spare. A very pleasant lady answered and attempted to find an answer in their FAQ's. When she could not locate one, she said she would ask an engineer and get back to me. Within minutes, a man called back and said according to the information he had, there should be no problem. The explanation given was that the sensor in the wheel must be very close to the receiver which is mounted down near each wheel.
Based on that, I found a great gentleman in IL who gets dealer takeoffs and purchased one. It comes complete, tire, wheel, TPMS sender, and center cap. That was a Thurs, on Mon the tire/wheel arrived in perfect condition.
Moving on to the RL, I did the following:
1. Before doing anything else, I deflated a rear tire to the point it activated the sensor. TPMS indicator light came on - system works!
2. Inflated the rear tire to normal pressure - TPMS indicator light went out.
3. Removed the donut spare and put in the new full size - TPMS indicator off.
4. Deflated rear tire - TPMS indicator on.
5. Inflated rear tire - TPMS indicator off.
6. Deflated full spare in trunk - TPMS indicator off.
7. Also deflated rear tire - TPMS indicator on.
8. Inflated full spare (left the rear tire deflated) - TPMS indicator on.
9. Inflated rear tire - TPMS indicator off.
10. Finished the install by tightening the bolts for the spare tire and tray and just to be sure deflated and inflated the rear tire again - still works as it should.
Based on this experience, it would seem that there is no problem introducing a full sized spare with TPMS into the RL.