A comment for what its worth:
I have a sloped driveway of stamped concrete pavers. The stamped pattern is similar to stone like slate - it is uneven.
I had trouble pushing my dolly, with the camper on it, around even the flatter part of the driveway. I finally broke two of the wheel hubs.
After a bunch of web searching I wound up contacting "Caster City" which specializes in casters and I spoke with Greg Howard who has been in the business a long time. He recommended some different casters for my application that I would have never thought of and I have to say that they work very well.
I recommend you contact them and explain your situation and my guess is they will come up with a better caster for you that will make it easier for you to move the dolly with the camper on it.
Now I realize that better caster will not solve the problem of a steeply sloped driveway but you comments about needing an hour to get over a 1" curb make me think maybe you need different casters.
http://www.castercity.com/
BTW: The prices I got were better than what was listed on the web page so don't assume cost before you talk to Greg. If you do talk to him ell him you saw a post on Wander the West from a recent customer recommending them.
Regards,
craig
Craig
What caster wheel did they recommend for you application?
Thanks.
Bill