Believe it or not, good 'ol contact (the type we've all covered our school books with works a treat. I have a full stone guard on my Tambo but there are still some areas that get hammered. Simply apply the contact over those areas before you travel (shouldn't be much with a good stone guard) and 95% of the stone chips you would have gathered don't occur. The big ones will still happen no matter what you do, this will stop the abraision type paint wear. Touch up the few that remain and Bob's your uncle!
Try it, it won't cost much, just make sure you peel it off when you return as it gets a bit iffy the longer it's on!
Regards
Mark