Removing satnav from car

I have just bought a Tom-tom via 180 (in Brisbane, Australia). I have also bought a 'Tom-tom beanbag dashboard mount. I am trying to work out how (after mounting the two products together) I can simply disengage the Tom-tom satnav from the beanbag and remove same from the car whenever we have to leave it parked away from home.
Is there perhaps some kind of proprietary adapter that will fit between the two products and allow for easy removal and reattachment of the sat nav, as desired. Note that this model has a fixed uniball & socket with short neck and round mounting plate that seems to need to be permanently affixed to the windscreen or dash. In this case I'll want to affix it to the beanbag mounting plate, but hopefully with an adapter that releases it also.

I hope some kind soul out there can help me, as it is proving difficult to get help from Tom-tom!
Cheers,
Kev