After I made silicone wing saddle seals using the wax paper method and still got leaks, I used another method.
I filled a glue gun syringe with water proof wheel bearing grease. After mounting the wing at the lake I just applied a bead of grease all the way around the wing saddle and WALA, completely water proof.
After removing the wing at the end of the day just wipe off the grease with a paper towel and inspect for water, you won't find any, at least from the wing saddle.
Also, put a bead around the base of the engine pylon.
I too braced the tail, But I used aerodynamic aluminum tubing. Slant the tubing to the front where it attaches to the hull for less overall flex of the tail.
You can mount the wing floats with the velcro provided but they WILL NOT stay on during a high speed taxi so tape them on or glue them on (with out the velcro) with Goo.