More than one way to skin this cat !!!
Fort Knox Safes, makes a holster type holder that has Velcro on one side. The inside liner is also covered in Velcro fabric that accepts the holsters. Not sure what your inside door panel is made of but is sheet metal. There is usually not problem in removing one and it does not interfere with the doors operation. .....
Now, my safe panel came with a velvet liners and plastic pegs. The pegs secures to the door by a S.M. self tapping screw. The peg, totally covers the screw. You caps that cover the screw heads from Home Depot. The Body of the peg, can be made from plastic clothes hanger. Cut each piece to about a 1-1/2" length. In short, you can make and install your own pegs. Let me know if you need more details....
Be Safe !!!