Norm

How would that work? Make up a heavy frame around the motor to support the boss and then push on the end of the shaft, I suppose
Need to be a pretty heavy frame
. Use one of those bearing separators in the middle behind the boss supported by the frame. I will be interested to see what you come up with.
Will the end plate on the log splitter be big enough to fit around the motor?
Should work.
When their is a will there will be a way.

What about a 15 ton jack pushing between a frame and the end of the shaft. Only thing that needs to be very strong is what ever base you use. Sides only need to be bolts like they are on the hydraulic puller as they are being pulled not pushed.

I will be very interested in what you come up with.

Jeff