Looks nice, i have made a small 3d printed mount myself using geared steppers with 1:720 ratio and have been thinking about building something big 3d printed as well. Using a wheel hub is a nice idea. 

As for balancing, what i learned with my steppers (also dont have a clutch), is that it works extremely well when not balanced at all, letting the weight take up the backlash. In fact i can put about 3 kg on top of it without any counterweights, the whole assembly being so small it is backpackable and archieving about 1.0" RMS when guiding. When that whole project is finished i am planning on submitting a build guide for it including all 3d files :) 

I am going to monitor this thread, please post your progress i am quite curious about it.