With only 1 camera, what angle are you going to use:
A. Over The Shoulder
Ceiling: If you are going to shoot over the shoulder then its either mounted up by the dome light or fixed onto the other seat with some type of arm. Up on the ceiling looking over your shoulder gives a nice view of the panel and outside especially for takeoff and landing. It won't be easy to see traffic (on the video) from this view but seems to be the best single camera view as long as you have audio. Getting the audio to this position sucks as the cable to a headphone jack station will be hanging in the air. And this location is probably the toughest location to mount a small power bank. When shooting from this position you can shoot wide angle or you can shoot a bit zoomed. Go more wide angle if you want more of you in the shot but remember the traffic, clouds and anything else outside will seem quite small. I like to use the gopro option that has the distortion removed (forget the name right now but is more zoomed).
Seat Back: The other option is to mount it to the back of one of your seats. This seems like a great way to get a great panel shot but maybe not so good for an outside shot. However, this position is a bit better for routing the audio cable and would be more convienent for strapping a power bank.
B. WindShield/SideWindow
This will give you way better outside views. If you think you will be seeing lots of traffic and want to film things down below, I like placing it on the windshield on my side so I can move it around to the side or point it ahead. Of course if you do this you'll be given right traffic LOL
So if you just know you'll be given right traffic maybe place it on the other side. What is nice about this position is that you can place a small power bank on the dash and if you are routing up a audio cable from a headphone station it won't have to "hang" as bad as from the ceiling.
Power
I have found that the "lipstick" sized power banks are enough to really bump out the battery life and yet be pretty small and light. As I understand it, the gopro will fully drain the external source first. Otherwise, yes...turn off the wifi and other setting right away. There is one caveat, if you use the gopro remote you have to leave something on. However, when the gopro smart remotes works it is nice if you want to keep stopping and starting several cameras at the exact same time (I do love that for 3 cameras). However, if the camera is over your shoulder or up on the windshield you can turn it on/off and start/stop recording pretty easily via the buttons.
Audio
I am a fan of having it recorded in with the video. I have a offboard recorder like Nate but once I bought the "correct" cable just having the audio already synched and was one thing less to fiddle with. Now, if you want to capture all of the OSH audio shenanigan's then running a separate audio recorder would be handy (or use your phone!) and do the clap! Remember, to bring in external audio to the gopro 5 and later you need their $50 audio adapter. There are a few more options for audio. Some headsets (Light Speed) have a audio recording support feature. And finally, you can use a simple lavalier mic (a tiny lapel mic, $20) and place inside a earcup of your headset and record to your phone. However, I am thinking you will need yet another correct cable and the aviation headset "correct" cable will probably run you just as much so why not use that cable and direct into your phone or camera.
Power+Audio
I could be wrong but I thought once you use the gopro audio adapter you can either pass power through it or use it for recording but not both. Man I hope I am wrong but thought I should mention it.
Settings
Unless you are really into this stuff (ie. Protune menus) I would go with most of the standard settings. If you really want something higher resolution than 1080p maybe shoot 2.7K but 4K takes up a lof of space and battery. Shooting 1080p at 30fps and a 64Gb card will give you way more recording time than battery.
Filters
I am fan of the camera having a ND filter (gets rid of the prop "bananas") if the camera's main view always includes the prop(s). I also like to use a circular polarizer to get rid of as much glare off the windshield, lakes, rivers as possible. But to get into filters means you need to buy more stuff and possibly a different housing. If want to get rid of this blur with big glass filters there are small snap on ND filters for the Gopro5 and later. Think ND4 or ND6 or ND8. Definitely don't use the ND8 or ND6 once you get into evening light (like 45min before sunset) as the video will get grainy. And don't even use ND4 once you are close to sunset. Hopefully not a problem for you OSH arrival and departure.
Since you are kinda new to this I would recommend getting the audio adapter and correct audio cable and then mounting it to the windshield (unless you have a easy way to ceiling mount). Buy a snap on ND filter and just film away. Don't be afraid to turn off the camera if there is nothing going on if interest. I would definitely just turn it on and forget it once you get into the busy arrivals phase.
