For example: how would you transfer a remote php shell when doing RFI in a closed network?

I recently thought about as well and I will probably code something myself.

Current idea is to give 2 ubikeys to my wife and my mother. Together they have a pw which can be used to decrypt a gpg backup with all documents and the master pw to my vault warden instance.

Also, take a look at this: https://github.com/potatoqualitee/eol-dr