I had one of those Harbor Freight pieces of junk for my car trailer. I finally threw it away. Your tow dolly is pretty lightweight. My suggestion would be to:
1. Hard pack the gravel from the rear of the motorhome so the dolly moves easier.
2. Replace the large gravel at the rear of the coach with pea gravel and hard pack.
3. Put a hitch ball on a riding mower, a golf cart or on your car and move it into place that way.
4. Dump your towed and buy a Jeep that can be towed four down....:W:W....Dennis