Mark, I made a four caster framework for my 20 ft IB to rest on, and that allowed easy rotation, for a 1500 lb load. Initially, I chose casters rated for about 500 lbs each, figuring 4 x 500 = 2000 lbs would be enough. False.
On rotation, unless the surface is very smooth, transitional loads rise and fall, and some of the casters failed. I went to ones rated at 900 lbs each, and they lasted. The ones in the photo look to be similar to the 900 lb ones I had.
Transferring the boat from the trailer to a framework or some dollies will demand some jacks and/or jackstands. I expect you already have those.