[bodywerks]

There isn't a single arf manufacturer out there that uses "ready to fly" weight, with a full tank of fuel. So you ended up with a 16-3/4 pound plane. It is easy to add 3/4 pound of unnecessary or overweight stuff to a 50cc plane. Your equipment choice isn't way, way overkill, but it is just a little. I could see losing 1/2 pound with lighter stuff, batteries in particular, and another couple ounces getting rid of all the HD switches - they make regs with built-in failsafe switches and you don't need an external switch with the smart-fly cutoff.
Also, if the plane is still relatively new it might still have water weight in it. A friend of mine lost 3/4 pound on a 75cc plane after re-weighing it two months later on teh same scale.