Here's the start of the servo mounting. I glued two strips of 1/4" square balsa down each fuselage side. 3/8x1/4 hardwood mounting rails sit on top of the balsa. I'm using the plastic tray that Futaba includes with thr radio sets. Once I get the CG set right, I'll glue the rails in place and add some balsa caps to lock them in place. The picture makes it look like my tray is a little crooked, maybe I'd better go back and measure again.