Do a respray and then 3M it. I did that with my E46 and it underwent 25,000kms of multiple US roadtrips. The 3M did it's job and not ONE chip appeared on the bumper.
Going to do the same on the E39 in a month or whenever it's on the road.
'12 M3 6MT Alpine White + Fox Red Extended | '09 328i 6MT Space Gray + Black