If you could, it sounds like an outdoor basement would be the best idea. You could still access it in winter, but it would also be visible too. Even if you hide the entrance, the temperature difference inside the basement would probably cause snow and ice to melt quicker above it, thus revealing its' location.

In Florida, this is impractical because of our high water table (don't worry though, in about 20 years, the booming population will suck every last drop out of the Florida aquifer, and our landscape will look like a teenager with really bad acne. Or maybe not).

Plus, it tends to get REALLY REALLY wet here. That tendency is increased in some years between June and December.

You might be better off storing it in a Self Storage Area, I don't think those got looted. Who would put a 72" plasma screen in self storage? Let alone anything truly valuable?