It seems to me that tongue weight would be a challenge. A standard tow dolly is configured with the axle directly under the car wheels to carry the load directly and keep tongue weight relatively light (neutral balance). Loading an 800+ lb bike plus a platform for it ahead of the axle is going to put something like 800-1000 lbs extra on the tongue and thus the ball mount. Total tongue weight could reach 1100 lbs. Ideally, the dolly axle would be moved forward several inches to shift some of that weight off the tongue. Of course, the axle must have sufficient weight capacity to handle the extra plus the car front end weight. Also, the coupler on the dolly might have to be uprated to handle the extra weight. Most dollies come with a Class II coupler (2" ball) with a 3500 lb rating. The modified dolly could easily go to 4500 or so if heavy vehicle is dollied.
That amount of weight on the ball mount may or may not not be a show-stopper for a big diesel coach, but it has to be pushing the weight-carrying capacity of the hitch receiver.