2x Houston Remodeler comments on taking into account interior ceiling height, height of door track and opener.
Even low overhead clearance openers take up space,
I use the 12 wide x 14 high door into the garage when I have the camper on the truck. Interior ceiling height is 16 feet. Garage has vaulted rafters to minimize overall height of the garage on the outside
If entrance to the garage is not level, need to consider height necessary for entrance angle.
My basement TC, with AC, on 4x4 measured in at 12' 4"
See lots of 5th wheels around here parked outside nice tall garages, because the door opening was too small ...
Whatever height door you select, strongly consider going with a 12' wide door. Outside dimension of my dually tow mirrors is just over 9'. I have to be extra careful when backing the truck in to the other 10' wide door openings in my garage. Very easy to catch and break a mirror when tired :o