Not sure how L2TPv3 Pseudowire fits into this picture given you're using dd-wrt. L2TPv3 Psuedowire sounds like nothing more than an ethernet bridge, something that is available using OpenVPN. I've done it myself many times when connecting my two homes. Sometimes I need remote access at the ethernet level rather than IP. And so I'll create a new VLAN and/or VAP (w/ no DHCP server of its own) and bind it to OpenVPN using a bridged (tap), site-to-site tunnel. And now any device plugged into that VLAN or using its wireless VAP has its DHCP requests sent over the tunnel and assigned by the remote DHCP server. And if you're DHCP server is using static leases, it can assign an IP based on the remote clients actual MAC address.