I have used the mushroom plugs. The newer the tire the more likely to find a nail/screw/pom (piece of metal) in the rear tire. My previous Roadsmart III had a mushroom plug in the rear for 15,000 miles. The current III's are cupping badly, it appears the asymmetric tread pattern and the hard/soft compound boundary on the front tire is exersabiating the wear. I am about to install the Michelin Road 6 GT's. The tread patten is symmetrical so may be the hard/soft boundary will not have preferential wear.
I have equipped my car which has no spare but run-flats with the mushroom kit and a small compressor in case I need to go more than 50 miles to a tire store. (They are probably special order as well. ).
The plugs are easy to use, I have the tool you turn with a hex wrench. Find the leak, ream the hole, push the tool in with the spike, undo the back body which pulls the point out but leaves the tube, load the mushroom plug, attach and screw in the plunger, pull the tool out leaving the mushroom in, pull the exposed end to seat, it probably is but pulling is to check, cut the exposed end flush, inflate.
The FJR with a flat back tire needs at least two people to get it on the center stand. The side stand tips the bike to far over to the right so a barrier, fence, something solid to lean up against is needed. I found this out when I had a rapid deflation on the Baltimore beltway. The back tire was flat and squirrely by the hard shoulder which had Jersey barriers at the side, luckily as it transpired. Of course you have to roll look roll to find the hole All the time trying to get the seat out of your ass! Talk about pucker.
I now have an amazon TPMS to warn me of impending inflation issues, would not be without it now. Best $50 farkle ever.
hope this helps.