Dear Mike!
I understand you, and I can accept your morality principles and theory! Albeit I keep that being moral i.e. acceptation of any definition, description, law about 'moral', mainly depends on one's conscious intent and decision.
You ask: "Would those cruel, hyper-intelligent beings (the ones you spoke of) accept it?" I don't know!
Please understand. There is no fault in either of moral theories itself!
But, you are wrong in that conclusion "If there's no fault, then hyper-rational/immoral beings are impossible"! That is not so! Whether those cruel, hyper-intelligent beings accept moral or not doesn't depend on how a moral theory is defined. It only depends on whether they want to accept it or not!
This is not a definition of 'my moral theory' - this is unfortunately a fact! Okay?
There may be one driven into insane very because one doesn't want to accept what he knows. He is propelled toward doing wrong=irrational (as you define) things even if he is very intelligent to know very well what he does is irrational, and insane.
What is his reason to do this? The basic antimony inside himself. Simply, He doesn't want to know or accept what he knows! This is much more a psychological disorder than what the pure logic can lie for being moral.
The most of us can accept and wish moral laws being anyhow defined, and can act using that laws! However I warned, and mentioned quite lengthy to you the biggest problem is, if there may be only few ones or only one, but high in charge doing irrational things rejecting moral anyhow defined, but affecting the lives of most of us.
Bye - Valeria