brobeson
I was looking for the same thing. Didn't find it and ended up putting some mudguards behind the duals. If you haven't already checked roadwing you might find something there. I called them several months ago and the lady I talked to said that they only made units for single wheel trucks at present but might make some for duallys in the future. If they have started it should be a nice unit. I looked at their single wheel units on a truck and the quality is very good. I thind their website is roadwing. com (not sure). Good luck with your search.
Sam Stokes