Having flown Cessna 182s with proper rudder trim, I'm spoiled enough that I want one as well :)
I've found several other builders who added rudder trim (link 1, link 2, link 3, link 4). It appears that most of them use the same recipe, originally conceived by Don Orrick, which involves adding a servo inside the rudder to control a rudder trim tab (video of it working):
|Image from www.myrv10.com|
As for the camera, my ideal setup would be some kind of "box" at the top of the vertical stabilizer where I could fit any camera I want (thus allowing for an easy upgrade to newer/better cameras as those become available), yet with the lens sticking out enough that the image doesn't cut off at the bottom by the stabilizer cap. I've seen several builders who modded the cap by adding a hole and molding around a specific camera (link 1, link 2):
|Image from Gaylon's kit log|
Another issue is how to run the wires to the camera (at least for power, though if I do use the G3X as I intend to, it supports video input as well). Apparently the easy way is good enough, which is to drill holes through the ribs and run conduits through them, with or without reinforcement plates around those (link 1, link 2). An alternative is to use the lightening holes and fasteners.