If it's really been sitting for 20 years I wouldn't even move it without new
tires and bearing service.
Its not all that hard to put it on blocks, pull the wheels and hubs, and get things taken care of first.
If not, think about the possible collateral damage to the trailer when a tire blows out while you are trying to tow it even a few miles to a garage.....
Also: Take a good look at the frame for rust damage as well, esp right where the frame exits the front of the coach.