Ohh, but if you could attach the Z axis systems being tried directly to the router with a bracket, it could work if you loose the adjustment lock nut. Then the plunging action would be smother that trying to build a holder for the spindle.
The only problem I see is the power is in the handle, and if the ring or other mounting system is used the handles might have to come off and so the power would have to be re routed.