A agree with all the others, Looks great! I built mine by my self, and it was a learning curve, and more expensive than I thought, expecially when I really messed up the foundation. I agree with the heated shop, and in my case Airconditioned! Makes a world of difference, and you can work on the GT's or other things year round.
Now for the critique. I know you are space limited, but bigger is better. I went from a 12X24 to 16X24, and wished I had did 24X24... nevermind, no matter how big it is you always need more.
I would look into a 6' roll-up door. 5' is rather narrow and some decks 60" or more may not fit.
I am not good with Roof's or windows, and it did take me three tries to get the opening for the 6' door right. Sorry no help there.