[RogerBW]

(writer of the Wives and Sweethearts campaign here)

I like to put the jump zones (natural or artificial, specific points or just "where you can turn on the FTL drive") a long way out from where the useful planets are.

If you have realistic space drives it takes a very long time to get anywhere, because there is no drive that has both high thrust and high endurance (specific impulse, or mps per tank in Spaceships terms). At TL10, the antimatter plasma rocket is your best bet for endurance with 120mps per tank, but it only develops 0.01G. The highest-endurance TL10 drive that gives you a "high-performance spacecraft" (0.1G) with just one unit is external pulsed plasma at a mere 8mps/tank.

This gets you isolation, but it fouls up endurance, because by the time you've crossed a few systems to go in to look at things and then back out to the jump zone your tanks are dry.

Put the jump zones closer in, and you can make more system crossings but you get less isolation.

Couriers are also a concern: if your FTL allows them to travel directly across multiple systems, you lose isolation. In W&S a fast message is sent by radio to the jump point where a courier is on station, the courier jumps and transmits it by radio (hours of delay) to the courier at the next jump point… but this requires a network of couriers, which implies a reasonably solid civilisational infrastructure.