Originally Posted by Jeff_H
I'm not sure where you are located but I bought a boat that was located in a pasture in Maine. I chose to use a boat hauler with a hyrdraulic trailer. The price for hauling the boat was identical to what I was quoted for a conventional hauler, and I did not have to pay for either a crane at the Maine end, or a travelift at the Annapolis end of the trip resulting in a big savings. While you may be able to rent a crane capable of handling 20,000 lbs, it won't be cheap.
Let me add to Jeff's note above that the hydraulic trailer of which he speaks is capable of picking up the boat and setting it down without any need for a crane or a travellift. A hydraulic trailer is what you want, assuming you have a paved or hardpack surface that the trailer can back into and set the boat down on.
If you have to get the vessel into a back yard with no access for the trailer, then it's a crane you'll be wanting.