I tried one style of child-proof latch on my old bus and they kinda worked. I didn't like how that style allowed the drawer or door to open an inch or two before it engaged. Cabinet doors were constantly opening a little bit then slamming closed.
I was on an old sailboat once that used elbow catches and they seemed to work pretty well. That boat had ~1.5" holes in all the cabinets that you could stick your finger through to disengage the catch.