Hello,
I'm a Linux\Unix systems engineer, VMware administrator, also certified Red Hat and VMware.
Also, I have good experience in Linux administration, troubleshooting, service installing and monitoring.
so, I'm interested in your project and I can help you.
what I understand you have 2 networks=N and 2 routers=R
So N<------>R<>----VPN-----<>R<-------->N