I suggest you consider a "dual power" wagon. I had one built that had the standard battery powered pump to run the hydraulic cylinder and a valve that allows the tractor's hydraulics to run the cylinder. If you'll be using a hydro tractor, make sure the the hydraulic fluid in the trailer's system uses the same fluid as the tractor.
With a dual system the trailer can be used behind a truck or other tow vehicle. Most of the trailer builders should be able to furnish what you want. Appalachian in Ohio is one that will build anything you spec.