By calling them 'saucers' I assume you mean you will cut the (sorta) conical pieces and mount a motor in that section.(?) I will state the obvious and say that if you take any of them and put a motor in the butt end, that you will need fins. Hence they are no longer saucers. The two on the left don't look like saucer potentials, but if you chopped the tops of the other three off and mounted a motor tube you might be OK. It's hard to get a great feel without seeing the dimensions next to a motor tube.
Makes me wonder if I modified one of my 4" AAW deltas to take a 18mm motor if it would work. (light coming on)