OK. I will try to explain a technical approach, because I am an IT guy.
I already have dataroot, in my Linux Debian box, in one volume and dirroot in another. Those things are setup into dirroot/config.php file.
I think you can use a shared resource from the other server via NFS (for UNIX like OS) or something like that.
Of course, this proposal is for trusted environment inside a LAN. Over Internet I think it can take some additional effort.
I hope this can help you. If it was helpful, I can give you more detailed information.
Good luck!