"Peter Dohm" wrote

P.S.: I really think that you are giving up a lot of your maximum power
in slowing a Soob down enough to drive a propeller at 1:1.

What you say about the shaft extension I don't think is applicable to the
question of a long drive shaft, which is what the post is asking. (I think)

The short extensions you propose (as working for Steve W.) are not long
enough to give a problem with resonance, like a long shaft would have. The
shorter the shaft, the higher the resonant frequency would be.

You are correct about the Soob giving up a lot of power at a 1:1 drive
ratio. It depends if the OP is willing to have that much weight for the
power being produced.
--
Jim in NC