The deal I mentioned in the other thread is that if you need a table saw, the one I mentioned above is free. But you have to pick it up. But you get to see where I live.
Since you mentioned clinging to a cliff-face, here are these. First how to put a foundation on a slope:
Then how to progress from a tent to a permanent edge-vertex dome:
Finally, a 40ft square that you could cantilever as necessary and have one level with a 24x40ft hole through it.
edit:
I just redid the math, a 39ft dome will cover a 20x32.3ft rectangle. It would have an hexagonal skylight at the top.