Here's a suggestion before you finish the project. Install two 2"x2" auto hitch receiver tubes on the frame at the top and bottom in the center both placed vertically. One sits flush with the bottom and the other sits flush with the top. There would be about a foot of open air between them. These would have the factory installed strenth collars and be pre drilled for just a few dollars each. Once welded on, you could them insert a removeable 2"x2" pole/crane like the one mentioned in the recent gin pole thread with a hook or pulley at the top. Since your design includes easily removeable forks, this would be a neat crane setup with just one easily storable removeable piece. The pole would be held in place with the two pins in the receiver tubes designed for the auto hitches.