Help Link Station 220 Backup

[Skip4Josh]

Hi Im looking for some help and my knowledge in this area is limited and i cant seem to find what im looking for even though i've been searching and im sure it can be done somehow probably fairly eaisly... I have two LinkStation 220's with 4TB(2 x 2TB Drives), I have turned off the raid function using the directions supplied by buffalo. I have one LinkStation installed at my home location(it is up and working perfectly and accesible if i connect to my vpn :) ), the second link station will be installed at my work location. Heres what id like to do i just cant seem to find how to do it... Both my routers are araknis AN 310's and are capable of VPN's(OpenVPN, IPsec, PPTP), I would like to Back up NAS Home files on the work NAS(in a password protected folder on 2nd drive) and vice versa) , this would protect me from data loss in the event of a fire, drive failure, etc. as files would now be available off site on a whole other server. I want the vpn to stay connected at all times (so that the nas's can back-up whenever they need to), At the same point i dont want my home computer network visible/accessible to the work network unless i use a specific computer to connect to my home vpn. so im thinking rather then connecting the two routers of using a rasberry pi at each location to connect to the other location and then point the NAS through the rasberry pi to the NAS at the other site.... how would i set the NAS up to do this? Are the rasberry pi's a good thought? Is there a better way or suggestion to accomplish this?  I appreciate any help Josh