I have a door going into a bunkhouse that is not visible from where the slide control switches are. On my first day of ownership, I neglected to close that door (it opens IN to the bunkhouse) Natural...
The trick about all this is having a switch that will either carry the larger current of the slide motor as the original does or adding the relay and the micro switch that operates on less current. The latter will probably be easier to do as parts are available from a number of vendors. Corvettekent links to a SPDT switch that looks like it would work well in this application.