I think BC, KA, and in some respects Eve Online use warp, or jumps as a "loading screen", but the actual combat is in a fixed "sandbox". Be it a Cube, Sphere, or Hex. In KA's case a whole star system can be inside that sandbox. I am not sure how they did it ether, but it worked very well. I would try to use KA's map system as a guide if you could.
There are a lot of things that Klingon Academy has done that have never been seen since. Like Ginsu. The huge system maps, and interactive terrain. Fighting inside rings, Asteroid fields, Gas giant atmospheres, etc. Plus the ability to use that terrain to your advantage, or it be used against you. Like what General Chang said. On a Klingon warship "Everything" can be a weapon.
True Scale, or 1:1 IMO would be a little over the top. Like what was said it would be "nerdgasm", but realistically it would put a huge strain even on the best of hardware. You can make some pretty convincing planets that do not have to be 1:1 scale. Epic Scale is good, but too much epic scale could come back to bite you, and take the fun out of it in the long run. We do want to finish a mission in a "reasonable" amount of time.
1:100 looks pretty good as a starting point. You can always tweak it from there.