I think a scenario generator would have certain presets, like how many craft per base, or how many pads free, crafts attached to station or docking ports free, number of orbits with space stations per planet.
It also should add certain random preset Prelude II bases.
If air traffic is to be added, it shoudl also have a preset of ship names and types and use playbacks. I think it would be useful for stock ships, because a playback would not record DGIV or other custom craft properly. I have tried to land a DGIV and playback crashes the ship.
Another non stock ship might be either landed, or already in stable orbit, not subject to playbacks.