I have included an image of the fittings included

First what I had was the bars with C on top and A underneath with the bolt section closest to underside of the bar so after separating i took the A's and dropped them down into the four pre drilled holes and thats where i am now stuck.
Opening the roof and unzipping the tent i can see the front bolts but the B's dont fit into the gap alongside the rail and i cannot even see how to access the rear rails from the underside.
Any and all help greatly accepted urgently or i am going to be forced into taking a shorter surfboard away that fits inside the rear cab