I had a 3 wheel battery operated trailer dolly for moving my solarium showroom trailer in an out of homeshow venues. Trailer weighed around 3000 pounds.
I once tried running it down an incline to get it out of the building, nose first, dolly leading down the incline. Not sure exactly what the incline was, maybe about 10% or so. I thought it would work ok.
Well, the darn thing nearly got away on me. It was all I could do to hold it from bowling the dolly over an me with it. The dolly wasn't too heavy, I could lift it into the back of my truck by myself. Maybe 150 pounds or so.
I only ever tried that once.....