The total length of wire from meter box to switch will only be ~25ft, 30Ft max. I picked up 12/2 w/ground. Will handle the 20amps and the length is short enough not to be an issue.

Inside the building I expect 2 runs of wire from the switch box of 25' or less.

I don't think there are any issues, or reasons to need the 2nd breaker box.....

Thoughts?