I should think a mechanical engineer with a bit of initiative
could easily adapt a garage door opener to control a boatlift.

My neighbor has one, it uses a gate controller (we found out when he needed a
new remote).
I have a stop switch on my lift. It is just a cable attached to the lift cable
that pulls on a switch and shuts the unit down if you go up too far. It was
cobbled together with off the shelf electrical parts. The cable also runs
within a grab from the dock, like the stop cable on the subway so I can
immediately shut the unit down from anywhere along the dock if something goes
wrong.