I'm in the planning stage of a porch that will span 16 feet. I would like to use 8" iron pipe - don't know the wall thickness yet - to hold up a four foot roof overhang. I will eventually have to check with my architect, but I'm just wondering if any of you experienced builders know if I can get away with only TWO posts for the 16 foot span? Thank you!!!! I'm going for an old mining cabin look, with a rusty tin roof, and have access to only 2 pipes.