Testing INAV on it now.

Update 5: Have done a few tests and only run into one issue. I was performing a test and had an RX Loss fail safe at about 1.6km (1 mile) out. It regained connection almost immediately and went into Rescue Mode like it was supposed to. I couldn't recreate it on a second run and have done testing since then even farther out without it happening. There are a lot of sources of electrical interference where it happened. Here's the video, you can see the fail safe at around 1:25. Other than that I haven't had any issues besides jello on the GoPro which may be caused by the arms being too thin for this length.

Update 4: Build is finally complete...for now. I have configured BF and INAV on it. I haven't fully tested INAV yet but BF is working well. I upgraded the antennas to the new Frsky ones for the R9 system. These are the antennas that should come with it, but I guess for the price they had to cut corners somewhere. No problem with any of the components so far, I just hope they are as reliable as they should be. Changed quite a bit along the way, VTX antenna, standoffs, ESC mounting (got rid of those cheap cases that came with them) and the power cable and cap, just to name a few. Now to see what it can really do.

Update 3: Everything is working and configured. GPS and magnetometer are working well and GPS rescue mode is setup in Betaflight and initial testing went well. Still waiting on upgraded RX and TX antennas and 3D parts, so not quite ready but close. No major problems so far. In the video below you can see in the upper right corner when I switch it into rescue mode and it takes control until I cancel it. I had it set for 50m rescue altitude, not sure why it liked to punch out to 100m. Something to work out.

Update 2: After much research I asembeld everything today and did a maiden flight. Seems to fly well but it's far from done, lots more to configure and I need a few things yet to make sure everything is installed correctly and safe during flight.

Update: Finalized and received all parts and began building. Have been researching a lot of info since I want to try my best to get this right the first time. Changed to a GPS unit with compass and flashed the FC to INAV to check it out and see if it flies ok with it. BF might give better flight characteristics but is weaker on GPS and compass features. If INAV doesn't work out then BF rescue mode is better than nothing.

Parts are on order. Using an AKK VTX I already had and a XM+ RX for now while I test, tune and work out any bugs. Once I finish that phase I'll have decided whether to go with Frsky or Crossfire for long range and whether or not this VTX will work for this. Might have to consider 2.4ghz down the road if I like this. I'll be adding a heatsink to the VTX for stability. I'll also be bottom mounting the battery and center mounting the Gopro to distribute the weight in the center horizontally and vertically. I can always change if that doesn't work out.