I tried a "home made" zero stop. After a half day of attempts I decided it wasn't worth the effort. Way too much precision involved, at least for me.
The next best idea was posted here, my searches have been unsuccessful, where a hole was drilled at the bottom of the turret with a dremel. Then when zero was set a small dot of white "paint" was dabbed through the drilled hole onto the scope.
Thus when the turret said zero and the white dot wasn't showing, you weren't zeroed.
Pretty good innovation, I thought.
I'll give it a go one of these days.