Lots of great ideas, I am liking the one of going through the wall completely and adding a backer plate. Securing the fasteners will likely be done with a spot weld.
The door is the entrance to my office, it is under the master bedroom in my house, all 4 walls are cinder-block, the doorway in to the room was chipped in, no windows.
My tools are kept in a separate building on the property.
The door also has 38 other fastening points, only accessible in the jam once the door is open. The tabs are there to keep things square in relation to the concrete. Once complete I am going over the entire exposed cinder block wall with plate steel, there is only one, the other three are underground, then all that will be hidden behind drywall, the security will be in the confinement, that room exceeds the footprint of the house, so it wouldn't be natural to look for a door there.
I will attach some photos, my "flashlight shelf" is in here too, just inside the door on the right, eye level.
I am not rich and hiding valuable stuff, it's just my stuff and a fun project to look after it.
The door in the paint booth.
Installed and partially open, the door has 3 1" bolts that work off the handle, 3 locking points.
Open
The shelf
Inside
Another angle
Another angle, the door off the middle safe is the basis for the door, just extended.
And the door from the inside.