Before the final battle scenario, I had been using the K4 a good bit. I found that you could be at least somewhat successful if you wait, watch, and be VERY picky about your targets. I spent most of my time tearing it up low on the deck so I could make a pass from low 6 on any con that was going in a fairly strait line and was as of yet unaware of my presence. I would sneak up on a con 600-800ft below him, and when I got around 200yds behind him, I would climb up, fire a single round with the 30mm and then continue up through the climb to avoid a collision if I only knocked off a wing or the tail.
It takes a lot of patients and you may need to take more than 50% fuel if you want more than 2 kills, but this is what worked for me. IDK what any of the K4 experts have to say about my shenanigans though.