but I don't have a squadron (I'm an unsociable loner

).
There's no minimum membership for squadrons, so creating one for 10 million credits and aligning it to the faction gives you that alternative colonisation route to resurrection - and gives you a little bit of tracking information for them even if not.
80 ships is definitely enough that it's going to be providing a significant stabilising pressure on the system even if your faction is not deliberately being suppressed - that said, I'm surprised that it's consistently pinned to 1%. Getting up to 2% shouldn't be that tricky under the circumstances.
only 3 of them own assets
Ah. This may be the problem.
Since around the Ascendancy release (it might have started a little earlier) systems which were part of Powerplay version 1 have stopped having mission influence do anything. This will make it very hard to support a faction which doesn't own assets if that's the case.
Your options in that case are:
- bounty hunt with a KWS, hand in whatever scraps you find for your faction, hope it's enough (vs 80 traffic it'll probably get you off 1% but it'll be slow). Any other bounties must be handed in out-of-system!
- missions ... where the destination is not a Powerplay system. There might be a bunch of new colonisations popping up around your system and missions run with a final hand-in destination in those systems (courier, cargo transport) should still work. Again, limits your choice a bit but you should still be able to run a decent number.