To see the instruments clearly and the outside will most likely require two cameras or 1 exterior camera and screen recording of a tablet session. In both cases, reviewing afterwards will be a PITA unless you edit them..which is a bigger PITA
I would expect minimum 1hr of editing time for each hour of flight!! Will you get paid for that second hour?
But you asked
Single Shot With Interior & Exterior Both Kinda Visible:
As previously mentioned you need a ND (Neutral Density) filter. It will basically limit the light entering the camera which in turn cause the shutter to be open longer and the interior will become a bit more visible, but not great.
I have been using a Variable ND filter and stop it down about 40% max. This gets rid of the prop "BANANA" effect (irrelevant for your lesson reviews). But variable ND fliters and wide angle don't jive at extreme stops due to a bright X pattern so don't set it all the way dark.
Now a graduated ND filter will be ideal. You position it so the dark side is up and bright side down. This will darken the sky to even the exposure with the darker inside cockpit. I haven't tried this yet. You can either buy a standard ring mount filter or a system where you slide in square ones (Cokin, Lee, etc). The slide in ones are big and the corners are sharp bit give the most control. The problem with the graduated ND filters is that anything between the camera and the outside window, such as your head, will look darker than your body below the glare shield.
How To Mount The Filters:
Well for Go Pros, they make slide on fixed ND filters. I have never seen a slide on Variable or Graduated ND. So, enter the Go Pro enclosure. I like the Luxebell ones on Amazon. You slide the go pro in. The enclosure has a round 52mm fliter ring. Then you can mount anything you like with 52mm or larger with step up rings. You will want to step up to maybe 72mm or 77mm so that the ND filter edge does not appear on the go pro wide angle image.
A Non Filter Idea:
Maybe forget the filters and just bounce a bright LED light off the panel. Now it will be closer in brightness to the outside. You'd still have the prop baNana effect though.
Alternative To Filming Panel 6-Pack:
In Garmin Pilot you can configure several instrument views. Select the one you want and then just screen record the session. You won't have IAS, but you'd have enough to match up to the lessons. And you could render it smaller. To get the best info, you'll need a AHRS Adsb in device. I am guessing Foreflight has a similar 6-pack view.
ATC and Intercom Audio:
Just buy the right audio adapter, about $25 on Amazon. Plug one end into a spare intercom jack and the other into the gopro mic input. Viola, no needing to synch separate audio recordings. You can see this in
@Radar Contact 's videos.
Best Go Pro:
Subjective. I started with a knockoff. I still like it for outside the plane. But the Go Pro is sharper, auto rotates if mounted upside down and the hero 4, 5, 6 Black versions have protune to override shutter speed and the awesome "linear" wide angle view. I am using a pair of Hero 5 Blacks. Buy them in the non retail packaging or refurbed to save money.
If you really need to see the 6 pack sharp enough to read numbers you'll need to have the camera probably on the pilot side window as stated by a previous poster. And change the angle/fov to not be super wide.
Shooting the go pro video is easy. Editing even just a 2 camera sequence is a big pain.
Another good alternative since this is for quick review is to instead record video with your phone and the audio cable. Just RAM mount your fancy iPhone or Samsung phone where you'd put the go pro.
Good luck!!!