Backing Plates and regarding SRS with Bimini
Rick, the plywood "backing plates" were about 5x8 or 4x7 inches (sorry I traded in the boat and am going from memory, and each side was a little different) but were kinda funny shaped, not true rectangles, due to the shape of the area in which they were installed. On the Bimini, I had one with my SRS. The bimini attached with one long pole to each side of the boat, and to the "backrest" rail on the SRS, with a shorter pole of course than a standard bimini would have had. When the bimini was not deployed, ie it was rolled up, it sat over the SRS. I am 5'11', and I could see over the bimini both when deployed and not. When rolled up, it I could just set my chin on the top of the roll. When deployed, I could easily see over it, as it was a couple inches lower then. It was a nice addition, lots of shade - I'd do it again. HTH!