Getting Second Rail in Place

Did this a bit differently, with the one long piece of C channel to block the rail from coming back towards me and the outside piece removed. I then used the outside piece and C clamp to gradually stand the beam up on the post so it couldn't go anywhere. Much better! Only real problem in this orientation was that the purlin on the forks was hanging out too far to the left (observatory) side, making it really hard to lift and maneuver that end into place.