I installed the controller for the liftgate out of sight but within easy reach just under the benchwork. Besides being convenient for me, it keeps curious visiting hands off:
With a 4 foot span, my arms aren't long enough to reach that from both sides. If I want the outside switch to be disabled, that's easy to do with a simple switch on the inside.
My goal is to have the two switches, one on each side. They'll actually trigger relays in a control box that actually controls the liftgate. There will be an interlock so that when one relay is activated, the other one is locked out to avoid the dreaded short circuit with opposing switches.