Do any of you CCers have experience with hitch cargo carriers? I'm planning a camping trip, and I will be hitching one up to the back of our Volvo wagon. I am concerned about the level of dirt/dust that might get thrown up on the cargo (two bicycles). Is dust/dirt a concern, or do things stay mostly clean back there when you're hauling things? I thought about throwing a tarp over everything, but they're tall enough that a tarp will obstruct my rearward vision with a tarp covering them.
Total trip length will probably be around 2,500 miles or so.