Sounds good - I'll have to make a trip to camping world I think. While it might be cheaper to get the stuff online, I have a feeling a walk through the store might be beneficial to put some ideas together.
I never thought about using a spacer - I would have just put a 12x12 up with some substance and screwed into that. But after reading your response - I almost wonder if I'm better off getting the longer "bar style" mounting brackets instead of the ones that are 2 inches wide and 6 inches tall (single arm style).