After watching th-cam.com/video/wsZCOl0H7hg/w-d-xo.html I decided I needed one for myself. Mine is steel, weights about 40 lbs and I'd like to make a version 2 out of aluminum with different rollers, but this will be great for a season. I cut out a bit in the middle where I'm untangling some standing rigging.
It went from a scary, multiple person operation and a not very safe Gin Pole that came with the boat to something pretty simple to do on my own, though moving the mast onto the base is still a bit of work.
I'm hoping to draw it up soon, but for my boat and mast rest, mine is 9' feet along the long edge (distance from the companionway do resting mast resting bracket). The wheels are solid harbor freight 8" wheels (www.harborfreight.com/8-inch-solid-rubber-tire-42427.html). They are two inches apart on the contact surface. The base is 19 1/2" wide (width of companionway) with barrel hinges between the moving frame and the base that rests on the companionway. I clamp it over the aluminum channel that the companionway wood slats fit in to prevent it from twisting while under load. I have a short piece of chain that I attach the main sheet to between the top of the tool and the boom bail (where the boom vang attaches).
When putting in the reinforcing cross members, make sure there is room to slip between them and down the companionway in case you need to grab tools or hardware while in use.
imgur.com/a/Rk8V3DB