I am thinking about doing something like this too. Let me ask a question....I'm trying to visualize a scenario. I'm asking this out of ignorance....
So, I think you are moving your 30 foot tether up as a you climb the tree and it is connected into your belay loop via friction hitch. Let's say a prussik for simplicity. Now, let's say your stick or hand climber gives way during your ascent and you are hanging from the prussik on your 30 foot tether. How would you add the belay device into the system and shift your weight onto it? I picture myself safely hanging from the prussik, then taking the rope, inserting belay device, putting in the carabiner, clipping into belay loop, adding auto block, but then what? My weight is still on the prussik and I don't know how I would get it over to the belay device...don't you need to have something to stand on remove the prussik from the system?
Sorry, if I"m missing something obvious here.....