Cisco WAN :: 3900 Routing And Bridging Multiple Interface Configuration

I know this is not a the preferred way to do it, but this just an interim network configuration until the Remote Site gets re-located and reconfigured. I'm trying to bridge and route traffic and hoping the community can offer a review of the sample configuration and/or some ideas to make this a reality.

Existing network is bridged across site-to-site private line (p-2-p) so 192.168.100.0/24 devices exist at both locations. In order to reduce bandwidth consumption across the p-2-p, the 172.20.100.0/24 devices (end user PCs and new to the environemnt) will be routed out a local Internet connection which in turn reduces the p-2-p traffic to just private network traffic for the two networks. That same network requires routing through the 192.168.100.0/24 network in order to access the private WAN connected to the 3900 router with IP 192.168.100.1.