ORIGINAL: JAS
The carbon pin is do-able. Just make sure to check it for wear every 50 flights or so. Since the rudder tray is only carbon/balsa, I would suggest that stays as is. The biggest culprit for weight that we've found in building these is equipment selection and glue. No gobs of glue and you can save an ounce or more. Just make sure everything fits close (not wedged in or loose with air gaps) and use a little epoxy to make fillets on each side of the pieces being glued, and you should be good to go.
I had the same question. I've been thinking of mounting the rudder servo in the tail. Perhaps there is a lighter way of tying the structure together because that "carbon/balsa" platform is pretty heavy. I'm thinking some kind of balsa truss.
Jim O