Hi Alan,
Gave mine a wash and quick wax this morning and after 4 years and 15k miles I found my first star crack on the off side rear wing below the light cluster. It wasn't there two weeks ago and the car has only done about 2 hours since. It's about the size of a 50p piece.
Whilst I'd prefer not to have it and was dissapointed to see it, I am aware from others experiences and threads that it does happen. I've not protected the underside of the wings and am at the same time fairly pleased that this is the first one I have got to be honest. I guess it's a bit of patina. If I was driving an Elise, for example, I think I'd be more worried about it, but for some reason with the 7 I'm less so. Not sure why, and belive me, I really am a polisher (and blatter too, hopefully in equal measures).
I'f it gets bigger or I get more in more prominent positions I may feel different. I hope you get yours sorted.
As far a protections goes, I guess some of that foam camping mat may be good with some thin sheet plastic on top... maybe.
PeteSV