Mast lowering
If your mast is pinned at the base so that it will pivot, I think you can lower it using a 4 part block and tackle (boom vang or main sheet tackle)attached to the forestay. I lower and raise the mast on my 23 ft. boat every time I go sailing to get under a bridge, and i do it while motoring to the bridge. since I'm doing it alone, I added a 6 ft strut projecting forward of the mast, but for a one time event, I think you and a couple of buddies could do it easily. You should do it on a calm day and have someone holding the mast on the centerline of the boat to keep from putting a twist on the mast step. Also, catch it with a boat hook or with two guys before it is in a horizontal position, at which point the load on the tackle is very high. My mast is 25 ft high, but is probably about as heavy as yours.