said by danny2k12 :I'll try this configuration, although it seems that I'm running out of wired ports in the room with the ActionTec, as it requires 2 ports on each of the routers used for the bridge only
With option #5, only one LAN port is required on each router. Actiontec "LAN" to DDWRT WAN port. DDWRT LAN port to Actiontec WAN port.
said by danny2k12 : Will the ActionTec LAN ports still work with option #5?
No. There providing WAN connectivity for the DDWRT router.
said by danny2k12 :What about the subnet of the device after the NIM100?
The NIM100 is a bridge, not a router so any devices connected to it will be on the DDWRT LAN subnet.