Hey welcome Rustbelt! I'm in a similar situation as you. Can't go wider, only deeper. What will you be using the extra depth for? If it's more for a shop rather than car storage, it shouldn't be too hard to put a header in the back wall and making a 4 or 6 foot doorway into the new part. If on the other hand you want full unobstructed space in both parts, that might present more of a challenge. In any case, you'll find lots of good info and suggestions here!
