About rail brackets. I doubt I have a picture, it never occurred to me to take one, but I build rail brackets out of Starboard commonly. Depending on how I feel that day dictates how nice I make them, but take a long piece about two inches wide, and an inch thick, and using a spade bit drill a one inch hole in it. Cut it in half in the center of the hole. You now have the two ends for the clamp, provided you saw ahead what you are building, and left enough to work with. (The reason I said a long piece is simply so you can chuck it). At this point, obsessive/compulsive personalities can have a field day. Countersunk bolt heads and whatnot, and if I have to describe that technique, maybe you oughta buy 'em outright.
I have tapped 1/4-20" holes into the stuff, but I think two well placed #10 S.S. screws work just as well. Drill a relief hole for the threads though, the stuff can split/bust. I can whiz one of these puppies out in about twenty minutes that Hulk Hogan couldn't snatch off of the boat.