Nice progress! Quick question. Can you remove the FPV camera/keep the VTX off for the maiden flight? That's my recommendation in general for any autopilot equipped planes. I've seen my share of "bugs" mostly relating to misconfigured settings result in -err- exciting flights characteristics.
It would just be one less thing to get damaged.
I've seen planes promptly go inverted, but still stable and controllable (usually somethings reversed), planes that oscillates/flutters like a dolphin on crack (usually bad PIDs), and planes that get a mind of it's own (going into an autonomous mode too soon)
For that matter, I usually put dummy FPV stuff on my UAV maidens until I'm sure the airframe works well with the flight controller.