Hi Len, the crane was designed for 7 tons...;-)...
The 2 spars probably weigh over 40 kg, a serious load to get aloft, at first I tried to pull them up through a single block, it was too much... A block and tackle solved that problem.
A Prusik knot just above the center works well. I suppose it could be done on a mono as long as the pyramid is tied to deck, since your boat is narrow the most important foot is the one on the gunnel, that one must be very secure!
It takes 2 of us to do, the most important job except for pulling it up is controlling the bottom which is dragging on deck, we use thick cardboard under it, as I pull it up, Jenia keeps it dragging along on it's piece of cardboard.
It works well, yet it takes time to set up, on the water it will be harder, building the frame could be your biggest problem, since mine was made on the ground, then lifted onto the boat. If you can dock side to the wall, then maybe you could do the same. Any other way you will have to erect the frame on deck, that could be a huge problem....
Good luck, and keep Junking....