SITREP - got both rear wheels off using the hammer and wood method. Changed the rear brake pads - very straightforward ; I didn't bother undoing the guide bolts but unbolted the 16mm caliper carrier bolts instead. However, nearly acquired a hernia lifting the wheels on and off!
I also fitted a stick-on "protector" for the top of the rear bumper. It is a genuine BMW part (82110029671) which I have not seen in the UK. I picked it up for $40 when I was in Scottsdale,AZ. Looks good, particularly with black paintwork.
I also tried to fit genuine BMW rear "off-road" mudflaps but I was not happy with the appearance - my X5 has the "Sport Plus" package which means it has the 20" wheels with extra-wide wheel arch plastic trims. These prevent the mudflaps fitting properly. These wheel arch trims don't seem to be fitted to USA models - the guy at Chapman BMW in Scottsdale could not find them listed. Rather strange, I feel. Has anyone fitted rear mudflaps to a "Sport Plus" model? There isn't an issue with the front mudflaps as the wider piece of arch trim doesn't interefere with the fitting.