Beautiful.
My solution was a "Panic Room" of sorts. I was rebuilding after a fire that gutted the first floor, so I had a clean slate. We redesigned the floorplan to "remove" a small bedroom. The old access was covered with a much needed closet. Access to the "Room" was through a hidden door (behind a built in bookshelf on hidden hinges).
The bookcase covered a steel exterior door with a combination lock, set into 4x4 posts for the frame. To secure the "room" we used studs on 12" centers (instead of 16"), then ran rebar horizontal every 12". The exterior wall was typical "wallboard" behind that was 1" plywood, then the studs, then more plywood, then wallboard on the interior walls. Finally we filled the gaps with shredded tyres. The rubber grabs onto cutting tools. Its not foolproof but pretty good.
I had always planned to add an alarm system that deployed pepper spray; but sold the house before I got around to it.
If I do it again (cant tell you hahahaha), I'll add a hidden exit door in the exterior wall, so that if Im ever worried about a breach that we cant handle with the armory stored inside all we would have to do is open the door and punch through the siding on the house.