The case of the awkward tunneling....redirect?

I have a FreeBSD machine that is a router that has been happily tunneling using IPSec/Racoon 4 sites for about a year now. Basically a FreeBSD machine at corp, and a bunch of RV082s at the sites.

The goal is to extend our phone system over those tunnels.

We have a Mitel system that is limited to only one IP address, no aliases. It is the router and server for the phone vlan which is

on the FreeBSD xl3 interface, is a connection to the Mitel VLAN address

The corporate office lan is xl1 and
Site1 lan is connected by the gif0 interface. All traffic flows wonderfully.

I, essentially, want to be able to ping and pass traffic through it like a gateway from

The RV042 prohibits sending subnets over the pipe that aren't part of the pipe.
I can't seem to figure out how to add extra subnets to the pipe.
I had a thought that I could "spoof" a IP address ( that tunnels back to

Ultimately, I'm stuck and looking for ideas. Anyone?