I can't see how those dolly wheels wouldn't make backing up difficult if not impossible. The reason you can't back up with a tow dolly or four-down towing is because, as someone put it to me, you're backing up a wagon, and the front wheels can go wherever they like. If you lock the wheels into a straight direction, your wheelbase is huge and turning is going to be hard (think about pushing that wagon, trying to change its direction, without turning the front wheels; the only force you can apply would be at the tip of the handle - or think about how much the tires on a 34' twist when it's turning while backing up). If there's something I'm missing, I would like to hear the correction.
1995 Airstream Classic 30' Excella 1000
2014 Ram 2500 Crew Cab with Cummins 6.7L Diesel
Sold but not forgotten: 1991 Airstream B190
Sold: 2006 F-250 6.0L Powerstroke Supercab