Adding bass to room with Sonos Port powered in-ceiling speakers

Hi All,

I have an open plan living area (somewhat T shaped) with 7 in-ceiling speakers that I am powering through a single channel amp. To connect this setup to my Sonos ecosystem, I am going to use a Sonos Port. I am using a Port+third-party amp, since I will need to use 3 Sonos Amps if I want to power this system.

My question is around adding bass to this space. It seems like you can't connect any of the subs to a Sonos Port. Could I work around this issue, using the following setup: Add an Era 300 (or any other speaker to the room) and connect the Sub to this speaker. Now, when I want to play music in this room with bass, I can connect the Sub to the Era 300, and play on a Sonos group with both the Era 300 and the Port.

Would this solve my problem? I don't need bass in this area all the time, and only when I am having guest over for a big party. I already have a Sub 3 and Era 300 that I can move from another room when needed.

Thanks!