Just an idea I had to approach the ships per sector limit in a more organic way (instead of set hard-caps of 50, 100, etc)

The idea is simple. Un-cap ship limits (or allow higher caps), but add some self-diagnostic code into the game so it detects if the FPS is getting low, it will reduce the Delta Time so the game runs in "slow motion" (giving the clients PC more time for calculations) until the game hits the FPS-min target again (say...40-50 FPS). If the game detects the clients PC is struggling then it could slow down time until the game runs at an acceptable Frame Rate again.

So even terrible computers might be able to run 200 ships on screen at once, it just might mean they do it at 50% game speed.

On better rigs this could mean hundreds of ships on screen at once, but with no worries for gameplay, because if the PC starts to struggle the game self-corrects the game speed.

Of course this suggestion glosses over the technical and coding hurdles to achieve such a thing. But I've seen it done in other games to great success. One thing to watch out for is to avoid having a completely unrestricted game-speed changes. This would mean wild variance in the game speed from second-to-second. Restricting the Delta Time to a Mean or Average per sector might be a good solution to avoid constant speed-changes.

Also, setting the minimum FPS target to a lower value would mean running at 100% speed more often, rather than after enabling this feature having the game always run at 90% or so because the target is never met.

____________________
All this aside, even in the late game, the most ships I've seen in a sector hasn't yet exceeded 200. But this settings option would negate the need for "in reserve" ships, and would minimize the impact of non-optimized game assets going forward, because the game would self-adjust it's speed, rather than having the FPS bottom out.
__________
As an added note, The addition of Game-Time altering code would allow the game devs to also easily implement player controlled "Slow Motion", if they ever decide that's a feature they want.