Now that the SpitzAX is my travel router, I’ll need more than just the one port on the LAN bridge. I could use a separate travel switch, but I have one of these too:
It’s a Asix 88179AX Ethernet that’s got a switch built into it, giving me 4 ports. I’ve installed the Asix 88179 package and it’s “eth2” on the Spitz. So, now how do I add this to the “br-lan” bridge via LuCi?
OK, figured it all out … sorry for the SPAM y’all 
Luci → Network → Interfaces → Devices → “br-lan” → Configure → Bridge Ports → Save → Save & Apply
What was tripping me was the “Bridge Ports” section; didn’t realize how to add an additional port.
That being said, if someone knows how to associate a network (device) name by a MAC address (i.e., "11:22:33:AA:BB:CC comes thru as “my-interface”), I’d really appreciate knowing how! USB “ethX” names change depending on when devices were connected, so I’d like something more definite.