I think the Dip is electrically insulated, so it shouldn't conduct if you use it. Only really cheap batteries would allow any of it to leak in. But if you dunk a whole set together (I assume you tape with cellophane or similar first) you have to be careful when slitting it open or just break it.

Heat shrink tubing (they make it pretty large diameter) might prove very useful. Not quite water tight unless you use the adhesive variety and leave extra on the ends.

I have some experimenting to do! :-) I like the idea of standardizing on one or two battery format, especially in an emergency. I can get AAs anywhere including the local mom & pop or gas station, but maybe not 123As...