LoL!
Might work.
I'd test the resin on something first; and whether it attacked the plex or acrylic case materials.
U-boot long engagement range will be about 8000 yards. That's 24,000 feet; divide that by 700, and you get 34' on my calculator, after rounding the quarter foot off. So, on the shelf in the other room is not far off <G>
Would be kind of cool to have a pin-hole video placed above the sub display showing the DE in a sort of "periscope eye view." Not real exciting video, but cool to see.