I thought this was simple! This is my take on what is happening, so if I am wrong please enlighten me!

For a 60 minute exposure, the object will rotate approx. 15 degrees.
That comes from 360 deg in 24 hours (approx.)
So the cradle would only have to rotate 7.5 deg. for a 30min exposure. That is easy to achieve ( I think).

Next, the cradle pivoting axis is aligned at the same angle as your latitude, pointing at the pole, also aligned with the center of gravity of the scope.
This means you only need one drive motor to keep up with rotation.

The procedure would be
1: Align the cradle level and pointing at the pole.
2: Set the Alt, AZ of the Dobson to center the target and then lock those pivots.
3: Turn on the cradle motor.

Am I missing something?

PK