My vision for Starcruiser II is a complete starship design system, drawing everything together so only one book is required. On top of this goes both a RP combat system (more abstract, but ensuring that all players have something to do every round) and a miniatures/battlemap/tokens sort of system. Both would be intercompatible, and would incorporate appropriate elements of High Guard, scaled for the "small-ship" 2300AD universe. Then a bunch of "historical battles", ships, and similar stuff. Ships 1000 tons and smaller would get deck plans, while larger ships would get general layouts, all marked for the "boarding party" rules. Rules for interface operation and combat. What happens with a det-laser in atmosphere?
Boarding pods and an abstracted boarding system for the battlemap-level system. Combat is section by section, favouring the "home" team, but results based on firepower. Firepower is a measure of numbers, training and weapons. Chance of damaging systems, and rules for damaging systems. Kept down to two pages of rules, based on my memories of Azhanti High Lightning.