Damn, dude - How big is this camera you’re talking about?
DJ and I read this one, and have no idea why you’re concerning yourself at all with “mods” or “expenses”.
Short and sweet. We do it for Real Estate folks and land owners all the time.
1. Mount the camera on a sheet of wood or whatever. No FAA requirements/regulations at all.
(Use something like a Bogen (Manfrotto) ball mount for good/easy camera control/aiming. We use a ~15”x15”sheet of 3/8” honeycomb - no flex at all, but a sheet of plywood or MDF would work just as well. BTW - A length of 3/8” foam pipe insulation around the edge keeps it from digging into the seat material.)
2. Remove the right hand door of the aircraft. Two pins. Two minutes. No FAA requirements/regulations at all.
3. Remove the back of the right hand forward seat. Two bolts. Two minutes. No FAA requirements/regulations at all.
4. Strap the camera/mount securely to the right hand forward seat bottom with the seatbelt and a good quality “bungie cord” or two. Nylon straps, whatever. No FAA requirements/regulations at all.
5. The camera operator can sit in the right hand aft seat. No FAA requirements/regulations at all.
The wing strut may become an issue depending on how tight/wide (and where) you aim the camera.
If that’s a problem:
Change step 2 to: Remove the rear baggage compartment door. Two pins. Two minutes. No FAA requirements/regulations at all.
Delete step 3.
Change step 4 to: Strap the camera/mount securely to the baggage area floor. No FAA requirements/regulations at all.
BTW - You can also secure the camera to any of the struts with a Bogen (we use them here quite a bit) Super Clamp and Magic Arm. We recommend a safety back-up cable be used when securing things where if they were to ever (for whatever odd/rare reason) fall off...nobody on the ground gets a headache.
Edit -
Note that removal of the front seat back only makes it easier for the camera operator to work with the camera when mounted on the front seat. It is not a mandatory step, if the guy can work over the seat back.
If so, mounting the rig over a modeling stool (solid box) on the seat will raise it up for him. (Been there-Done that...)
The bolts holding the seat back on are no big deal to remove. But you may have issues with removing the decorative plastic trim pieces if they have become brittle as most do over the years.