I may regret it but I chose to ignore the general sentiment of the group and went ahead and purchased a bra from Fancher's in Ypsilanti, MI.
http://fanchers.com/70/Sprinter Stuff.htm Call me a boob if you want but I think it will work for me. I stopped at their shop after dropping my daughter at Metro Airport and liked what I saw. The owner has a 2002 Sprinter and had failed to follow his own advice and left the bra on for a year and a half - this with the van parked outside. While I was there he took it off and it was surprisingly clean underneath and not marred that I could see. I think I will be a little more vigilant about taking it off and cleaning it, waxing the hood when I do so. It does look better than the acne spots
One advantage I have is that I park my van in my polebarn, so it is out of the sun and the weather except when we are on the road.
Fancher said to mention that if you purchase two or more items at the same time that you can take 10% off the whole order. As it was, I just got the bra, paying $80 for it.
Tim