This is certainly not overkill, as virtually everybody has fleets equally big. When your neighbours have three thousand baseships on your borders, you better have an equivalent fleet nearby.
The game isn't called "Return to Hell 2" for nothing after all.
I gather the turns are run offline in this game? Even my modest NGC5 (a mere 4.5 mb unzipped, without the combat log, above 3 mb last turn) can no longer run on PBW.