I'm not a truck camper...don't know much about them. If this has been posted before, I apologize. It's a slow day and I'm bored. So.....is this possible?
If your tag axle ran off the truck frame or receiver with only a horizontal hinge or rotating axle, I could see more benefit (you could even run a receiver off the tag for a trailer). If the TC was somehow vertically hinged to the forward part of your load bed with sufficient cab over clearance, a tag on the TC could serve its purpose.