Yea,you can be the only one,I just set up a "test" online cc...all you have to do is put a password on it,and nobody can get in.
The biggest advantage is that you can get updates alot faster without waiting foe them to come out in patch form (if I understood correctly)
I only have 1 house rule,and it's mainly for myself. I don't call a million audibles at the line on offense,the only thing I may do is either flip direction of a run play,or set my line to block in a certain direction,depending on where the blitz is coming from.
On defense,the only thing I do (sometimes) is shift my lb's to the strong side (if run) or do the same with my line,really nothing out of the norm.