Show me a shop, and I will build to the max allowable! C asters on the jig make it doable!
True ... put some big casters on the corners, keep the shop swept, and hide a hydraulic jack and some blocks under the boat while you are building. You can roll the boat clear up against a wall while you work inside or on the other side ... use the jack and blocks for leveling the jig as needed. Been there, done that....
If you completely encapsulate parts with epoxy to make them waterproof, you can temporarily store them outside with just a little shelter while you work inside too ...
Some people build temporary garage extensions, tarped up, to make their garages longer. I heard of one guy that had the wood header above his garage replaced with a steel I-beam so he could squeak out another 8" of height out of his garage door for getting his boat in/out. If you're creative, most anything can be done.
Brian