Default Bridging LTE to Ethernet (N7 2013)

I have a Nexus 7 (deb) that I'm planning on building into a car dashboard, and there might well be a few other networked devices in the vehicle. Rather than use WiFi, which is less reliable, I'd rather use ethernet to connect these other devices.

EDIT: To achieve this, I'd like to bridge wlan0 and eth0, and then just use the built-in tethering.

I'm running the ElementaX kernel to get the OTG+Charging feature, but it looks like that kernel is missing the appropriate modules:

root@deb:/ # brctl addbr br0
brctl: bridge br0: Package not installed
1|root@deb:/ # brctl show
brctl: SIOCGIFBR: Package not installed
1|root@deb:/ #

I'd go post in that kernel's thread, but I'm new here, and am not yet allowed to post in a developer thread.

So, am I right that I need some kernel modules built? Got a good howto on building existing sources on OS X or Ubuntu we can chat about while I rack up post count?