Front or back?
For the front I used a pair of the Clippan general fit retractables.
Rear is a lot harder, for rego I needed to get brackets made up that would support the retracting bit on the rear shelf, keep it far enough forward that it would fit under the window, far enough back that it wouldnt foul on the seatback and be anchored securely on the underside of the shelf (which isnt flat if memory serves me right. I did this by ripping out the rear seats and carpeting the back instead, and making up a carpeted solid panel to cover the ski portal