Quick Google search found these:
http://www.powerdolly.co/products/fifth-wheel-dollies
http://parkit360.ca/shop/5th-Wheel-Power-Dolly-Transformer-Parkit360
http://www.powercaster.com/index.html
If it were me, I would rig up a ball under the forward end of the frame, and lift it there. Instead of trying to do it with the pin. And that opens up the powered dolly options, not limiting you to fifth wheel designs. That second link above works that way.
A forklift would be a really good way to go, if you have the space for that.