Here is some data that may help. Don’t know why it is missing from the Tesla tech page.
My 9’-6” fits perfectly with two thirds of the rear seat down and front passenger seat as flat as possible. Unobstructed visibility to side rear view mirror and windows. Front of board is two inches from dash. No padding necessary. With a passenger in the rear seat, the board has to tilt up a bit but the rear view mirror is still visible if I lean forward. With a passenger in the front the board is pretty vertical and the windows and mirror are obstructed. Here the rear camera with the side repeater work great.
My 10’-2” also fits but over the dash and needs a protecting pad. You could probably get a 10’-4” in but not much more. You need the rear camera and can get a passenger in the rear and maybe a small one one in the front if you recline the seat more than you should for safety.
Here is a shout out to Tesla for the waterproof key card (don’t forget to power down your phone when heading out) and “dog” mode which is really “don’t melt your wax” mode when running errands on the way home.
