Believe it or not, there are rules in the park regarding the size of the sheds. 10' x 12' is allowed. Mine was 9' x 10' when I bought the place. It is part of the carport, using the carport awning for the roof. I decided to add the three feet toward the east edge of my lot. First I had the cement poured, then the awning extended. With that done, I was able (with the help of friends) to cut the east wall loose, move it, and build filler sections.
As my park model sits on a corner lot, part of the purpose of the shed expansion was to accommodate the Harley. Dave, Mark and I had already installed a roll up door on the north side of the shed. The siding removed for the door installation was saved for the expansion. I was given some other pieces of siding saved from another shed job to use on the other side.
The whole thing turned out pretty good. No - I won't work on your shed. One is enough.