I could be wrong but is seems that currently the only difference between Lite sub and f2p is that Lite subbed people don't have to play on android. While I do agree that the ability to play on a computer is well worth the price, there should be some more differences between Lite and f2p so that people who are stuck on a tablet still might choose to upgrade to a Lite sub. Some ideas could include slightly different level caps, or earning crystal at a different rate, or different crystal prices for unlocks.

I was going to create some other exclusive ship type thing, and make it available to Lite subs who subbed for a year in advance (and also to regular and long-term premium subs).

Haven't gotten around to it, obviously.

I welcome feedback on other ideas for improving the up-sell on Lite.

I used to think f2p was capped at level 3s while Lite Sub was capped at levels 4s. But I think the Levels are always capped at 4s now? I also think f2p should be "politely reminded" that the game is so much cooler if you pay for it once in a while if they aren't already.
As far as the improvement of lite Sub goes, maybe give them a bunch of test missions that can be taken once you subscribed for the $1 buck subscription. In said missions you'd get the Chance to test out some of the more advanced ships that a full Sub would offer (such as the faction exclusives, maybe even once pilot a Trident in an in-sector scenario).

Fly safe Incarnate! The idea with the exclusive ship model sounds fancy. If you're short on time, just give us the Anniversary Vulture again. I wouldn't be opposed to a second release. :P