I have two steppers which are somewhat successful at single-handling the mast stepping. Hopefully this description of my work in progress can help you in your decision making.
One is for the beach where my H16 is stored most of the time, and the other is on my trailer.
For the beach it's simply a 2"x2"x10' piece of steel with a ~$24 winch mounted chest high and a pulley bolted at the top. I temporarily strap this rig to the back side of a 3' high piling in front of my boat. Problem is that whenever I try to raise the mast single-handedly and by winch alone the boat creeps forward and the mast goes no where.
The pulley is well above the stated 30" minimum height difference spec from Hobie but it doesn't seem to matter. My only solution right now is to have someone lift the mast to shoulder height at the rudders and then the winch (and I!) can take it from there. Lateral movement is taken care of by tying the trap lines to the front corner castings with a short spare rope. Once it's on it's way up the system works great and is very stable in high winds.
For the trailer I mounted a winch to the mast stand about chest high. I built a mast stand extension out of 1"x2"x40" steel and mounted a roller to the top. Then I temporarily bolt the extension (with large wing nuts) to the top of the mast stand and thread the line from the winch through it and then to the forestay. Voila.
I just got finished with the trailer mounted stepper this week and haven't had a chance to try it yet, but with the extension that high and the boat strapped down to the trailer I shouldn't have a problem, I don't think

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I'll keep the board posted. I can get you pictures if you want. Otherwise good luck!