I am fabricating rails to support 2 seats for my boat. The rails will span roughly 18-20". Estimating that the average person sitting on the seats would weigh roughly 200lbs, using 1" x 1" square 6063-T5 alloy aluminum tubing, would 2 pieces of this be adequate to support the weight? The seat has a 12" x 5" square base that would rest on the tubing.

Thank you,