Having a big steel box underneath your boat is a very bad idea for several reasons.
-It basically is just a giant scoop and that will completely stop you when the frontbeam hits a wave.
If the sail flushes out while a wave hits you have no wat to retrieve the sail without destroying it.
But what are the odds? One in a million?
-In a normal pole-mounted snuffer the sail has an opportunity to dry whilst sailing upwind.