So, I'm not the best with this stuff, but since the Pittsburgh region is kind of a Spiceworks dead zone for some reason, I'll try to help out.
If I'm understanding your desires correctly, it sounds like you need a layer 3 switch that can route the outbound VPN traffic through a secondary gateway. Alternatively, if I'm not precisely understanding your situation, enabling split tunneling on the VPN should do the trick without a second gateway. It would automatically separate the VPN traffic out and let the bulk of the traffic go where it would normally go. There are situations where that won't work, but they're not terribly common.