Any chance of being able to provision a second address? I didn't see any mention if it on the rate card. Modem is an ARRIS TG1682G in bridge mode.
You couldn't get a second public / WAN IP address on that gateway anyway.... Why not just use private IP's on the LAN of that device out of bridge mode ?
No NAT in bridge mode. Use case is ease/convenience (and fall back options) for gradually migrating over to a new FW, without disrupting existing critical employment connectivity.