Well, now that I am awake, there are some other things I thought about.
Two garage doors is the way to go if you run your joists from one side to the other and plan on stick building an attic space up above. The space between the doors would be the load bearing post to support the beam you would need to run from front to back. Of course you could run the joists front to back and have the beam go from side to side allowing one wide door.
Save some money and omit the window on the RV side due to the big overhang and that an RV would be blocking the view. (and light)
Move the bathroom back to the storage space area, but tack it onto the space you already have. (On the left, heading out to the storage space.) If you made it as deep as the storage space, you have the room to add that shower...
On the inside of the garage (opposite the bathroom wall), have a sink with an eye washing station. Maybe skip putting in a bathroom window. Just another area where someone could get in.
I'm sure you'll end up with a way-cool space. Enjoy the ride!