What you need to do is take off your door panels and find a good place to mount the switch opposite of an opening in the door's sheet metal. Make sure that both doors have the same opening in the same place. Then you'll need to cut out an opening in the panel and the padding that looks like the curved part towards the middle of the switch plate WITHOUT cutting the fabric on the outside of the door panel. Go to the front side of the panel and cut a slit in the fabric in the middle of that opening. Then you need to drill at least two, and probably four holes in the panel from the back side, with corresponding holes in the switch plate, again without going through the fabric on the outside of the panel. From the outside, put small flat headed bolts under the padding and under the fabric through the panel using a dab of glue to hold the bolt heads in place. Then, after the glue on the bolts dries, from the back side of the door panel, pull the fabric through and glue it to the back side of the panel. You will need to make relief cuts in the fabric at the corners of the opening to make the fabric lay down smoothly. Then mount the switch plate on the bolts, put either capture nuts or nuts with washers and lock washers on the bolts and tighten them down to hold your switch plate in place. Does that make sense, or would you like some pictures?
No one lives forever, the trick is creating something that will.