One thing you may want to consider is that by being secretive about how the security of your system works is that there is no information on our end how it’s protected.
In the past when I considered building a vault which works quite similarly to what you are talking about I planned to have the entirety of the vaunts contents contained within a level 5 obsidian cube, with the only access being a passcarded door.
If you were to provide some information on how it works, without necessarily providing a schematic of the design it could prove helpful for building a more open and trusting relationship.