.....I'm at a little loss as to how you are limited to 8'11" if you have 10' walls and your door is on the gable end. The gable end is non-load bearing so you really don't even need a header, and even more any header should be able to be placed on top of the walls, so nothing would stick down except your door itself.Tad
8'11" only leaves 12'1" to play with(if it it is a true 10'). The header will be required for the srping attachements, as well as the amount of space needed for the track to turn towards the inside of the shop.
