Yah, I was trying to figure that one out too.
I currently have SRW truck and take it to the wash all the time. I wrote them (Brown Bear in WA) and they can't do DRW trucks.
When driving around in other states, at the U-Wash they seemed to have the Washer move around the truck.
So I'm wondering if that might work.
You just pull the truck in to a marker and then sit. The washer brushs etc, move around you. I'm thinking it might work, haven't been to one recently to ask but looks like the sensors will account for the Dually??
Dunno know.
Otherwise, will plan on using the U-wash stalls.. Wx over here, PNW/West it's not as bad as the East with the Salt/mud etc, but still like to keep'er clean.
Watching for solutions, thanks..