Strategic combat is never going to give you the fine tuned control that you are looking for. What you need to do instead of trying to figure out a way to manipulate it like that, is to learn the system and adjust your strategy accordingly.
With strategic combat you don't get to be Sergant Rock storming the bunkers, or even General Patton leading from the front. You are General Eisenhower, or maybe even President Roosevelt. Developing an overall strategy, building and amassing the fleet, setting the objective, and then sitting back and praying the troops manage to take the beachhead.
You are always trying to figure out the least number of troops and ships it will take to conquer the planet. That's the wrong way to think about this. You need to factor in some chance, and mistakes, and build a fleet and landing force large enough to account for that. You want to pick your enemies weakest point, and exploit it with your strongest force possible. Overwhelming force if possible.
Think of it those terms and you start to see the beauty and realism of this system. Get hung up on the nuts and bolt and you will go crazy.
Instead of "What's the minimum amount of ships I need to take this planet?" think "How many ships can I spare from other areas to conquer this planet with the least amount of tactical manipulation?" It's the big picture man. You gotta get the BIG picture.
Geoschmo