Yeah, I'm leaning towards getting them one-piece. The other way, I'd prolly bolt through and through a couple times on each side of the splice.

Next question: How do I make the connections between the braces? I can see I might have trouble doing that in the plane parallel to the tramp. My diagram here has 3 members of the brace in the top view. The front view shows the rails resting ontop of the seat brace.