Wow Jimmy, your thrust line looks really high. Must be ok though.
You can see how I cheated on mine by mounting the tail servos externally and ran open pushrods for the ailerons. It was much easier to build (it's actually my second) and can still be used on water. I don't play on water much, but it works fine.
Weight realm matters on this one unless you over power it. I took 3-4 oz off on the 2nd build by using foam safe CA instead of hot glue and it was night and day for.performance.