(Now that the demo is out, you can see the following for yourself)
There shouldn't be any problem making capital ships absurdly slow in combat but fast in strategic move in SE5, since there is what amounts to a "Combat speed per movement point" value in the vehiclesizes.txt
The restrictions in the same file will also let your force the number of whatever components, if not their location.
The real question is whether it you want the mod to be loose and use the physics of the SW universe... or if you want the mod to try to force a lot of story details.
There's a good quote about gripping too tightly in SW