I'm going to look more closely at the repair kit with the guys at the facility where the vehicle is- they maintain a lot of iron, quite a few racing cars and the one owner has a M3W so has given his personal attention to mine, which is there for a bunch of things including paint protection. Yes, I had contemplated an unmounted spare, not pre-installed on another wheel. @PaulV raises a good issue about impacting the boot which is thin aluminum skin. There is a company in the UK that makes a strap down mounting kit with pad for for mounted spares but I need to do more digging. Thanks, all!
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