I've built a tripod using three telescoping extension poles, the kind they sell for using with paint rollers. It works well for holding the mast at whatever height is convenient for whatever it is you are doing. It makes a great heavy-duty adjustable tripod.

I'm not that keen on using the tripod for single handed mast raising for a few of reasons. First, if the tripod is set high and close enough to the back of the boat to get a good angle, there a chance of a one of many dangling cables snagging the tripod and tipping it over into the back of the boat. Dinged a transom that way. Second, at low angles there is a lot of foward pull on the boat. I have my tie-downs arranged to resist this, but I'm not happy with the amount of forward force on the mast step ball. Third, since my mast must be turned sideways at low angles, lifting with the forestay or a trapeze wire does the wrong thing. So, this year I'll be working on a gin pole.

Just some issue to consider. A tripod may be all you need.