You could put a water sensor down there and keep your privacy in tact.

I would be against it personally. That said one that covers the entry way might be acceptable but would be better if it was out side.

Now if you had it installed and only used it when everyone was out side of the house that could be reasonable as well. Personally I doubt it’s to spy on you just wants a way to know whats going on when no one is home.

Maybe some combo of sonoff type relay at the light fixture, and battery operated button instead of the old light switch?

This would work I think.