Omega is correct, the Eclipse was ordered by 0 BBY/ABY, and do remember that Palpatine is the one who ordered it, but since he's dead, and there's no Galactic Empire in the galaxy to direct it's construction or can even pay for it. It does not exist in this setting. Same goes for SSD's like the Executor-class, it did not exist twenty years ago and would relatively be new and just stating in the setting. I'm sorry, but you're going to have to do some rewriting.