I guess I hit the panic button and ran here too soon. I found ground, the black wire to the right connected to my awning motor control switch.

I can tap into that big black wire but that will be a more invasive effort than connecting to the thermostat. I'm going to try the thermostat ground 1st and see how that goes.
A little back story: My FW has a failed LED strip integrated into the awning tube. I'm replacing that with a strip that mounts onto the camper side under the awning. The power switch and wiring to the outside location already exists. I can use the ground wire on the outside for the LED side of the controller. I just needed to find a ground for the 12V input side of the controller.
Thanks