I may try this at some point, but the toughest part of my mast raising is getting the mast back far enough over the crutch to pin its base, because of the spreaders. These photos look a bit different than what I have, as I can see that when the mast is in the crutch, before the rig has been used to start lifting it, the spreaders are forward of the crutch. I have a Z-spar, and maybe the position of the spreaders is a bit different that this pictured mast.
I did something similar to these pics, built a wooden attachment with a trailer roller at the top that I bolt on to the metal crutch. I leave the metal crutch in its lowest position (the one used to store and transport) and bolt on my extension. That extension is the right height so that when the mast is pinned and rests in it, the mast is angled high enough to clear the sliding hatch. Attached is the only photo I have at hand, but you can see the extension. I did not do anything to angle the extension toward the rear, and the slant of the transom positions the top of the extension (or extended metal crutch if used) a bit forward of the pintles. When I slide the mast back, rolling it along the roller, the spreaders stop it from rolling back far enough to attach the pin on the tabernacle. I have to lift the mast at the spreaders over the wood sides by the roller and move it back about 6 inches to get the mast base in the pinning position. That is a PITA as it is somewhat high to lift.
I have thought about ways to mount the extension so it is angled back a bit, but have no good design that would be easy and structurally sound. I may have a weld shop cut the metal crutch and reweld at an angle with some sort of strengthener.
Do others with a 23 find that the spreaders must be muscled aftward over the crutch to pin the mast? Any good solutions to this?