I think you are over thinking it. The electric motor is a completely sealed unit with it's own breather. Toyota took into account water when developing the unit. If you heat shrink all your connections and load up the plug with dielectric grease I don't see it being an issue at all. Besides if after all that I do blow an electric motor it is at that point I will consider going the cable actuated route. Why would I spend $1k on 2 new motors when I have completely good working ones now? Here is a thread on the subject:
I didnt say buy new motors for a laugh.... i didnt say rip em out and replace with cable actuators......i didnt say the factory ones were crap... i didnt say your wiring was going to fail..
i think you over reacting to my over thinking of why I (as in ME) would go cable route.
Now, get em wired and lets go wheeling