Currently upon testing, I've only been able to make projectiles live for ~330 or so blocks, which... is alright, but puts a damper on an artillery bombardment idea I've been coming up with.

Recently, Paper implemented a system where server owners can set a non-ticking chunk render distance that will show entities, but will not allow them to tick. The developer of Paper also mentioned that you could add a chunk ticket for the projectile when it passes through a chunk to allow it to tick until it exits, thus reducing a hit on a server while allowing for even greater range on a projectile.

I'm willing to pay some sort of bounty to have this change implemented, as I know there are still quite a few people not on the Paper or Tuinity wave and it would disservice them to include this update.

Maybe, it would be easier to despawn the projectile and respawn it in the chunk of impact. But that still involves a lot of testing.
Do you have a developer which could implement it, I very busy with other projects.