1) The streamer crashes too easily, IMO. It drives fast and you can get a lot of flight time when you jump. You'll still be an easy target and crash at any enemy fire, there is no real need to make it crash on its own that much (like on the hills of twin peaks).
ImpactGroundResetPhysRiderThresh easily could be doubled, since it was not meant for "real" and fast vehicles, but just something that moves a bit faster than regular walking.
2) Re-binding the keys 1 and 2 not only changes the default weapon keys but also the keys for switching vehicle seats. Maybe decouple that, though it is just minor and won't affect many people.