I don't know exactly how to describe this but it would be cool if there was some weight effect with the free cam. Means now with the mouce you can't really have smooth moving. As soon you move it it is instant and it is really hard to move from one site to the other without having jittering. It would make recording vids and fancy angles and stuff like that a lot easier. Obviously not high prio I guess but somehting to consider. Cheers
I've heard of people mapping controls (throttle, brake, steering wheel... or joystick) to the camera for recording videos so they have better control than the mouse offers. Have you tried that?
As Emery said, try binding your camera controls to a joystick or some other analog controller like xbox controller or whatever. I'm doing all of my camera movements with my joystick (T16000M). It works pretty well but still, the whole camera thingy could use some love from the devs.
There are a bunch of settings, in the controller.json file, which sound like they might be of use. I have edited these in the past, to speed up moving the camera around. There are some settings in there, to do with freelook acceleration when using a mouse. Hope it helps.