It should hit reasonably hard and effect the bubble. It would also give some purpose to the other trades, mine for materials because we need resources at x to fight the invasion, we need food at Y for the evacuees, those evacuees need transport to Z etc. Everything should effect the outcome so everyone can play a role in keeping the bubble safe. Including things like stealth missions behind enemy lines etc and exploration missions to find places to go should we be forced into retreat.
And plenty of opportunity to show off effective war builds for those that love RNG.
Places should burn if we fail though. Basically like a giant CG.
You missed Pirates off your list.