I'd suggest, after waxing, wrapping some cling wrap (Saran Wrap) around the neck, securing with a rubber band, encasing in concrete, and keeping the whole in a safe deposit box.
Actually, your plan sounds reasonable, but I haven't heard of anyone here actually doing it, so I think you're on your own. One thing I can suggest seriously is marking the level on the neck with a Sharpie, and rewaxing at the slightest sign of evaporation. You should be okay. I think.
(Mr Tattie Heid's 30,000th post, ten years hence: "Sorry, ardbug! What the hell do I know?")