how do I know what I'm approaching?
Chronographs are a good indicator. My experience is that QL is very good if you actually measure your case capacity, brass length, and COL. Either of those are going to be better than the discredited case head expansion or pressure ring measurement. I'd probably use the software as a start, and then fine tune with the chronograph.
With 150 grain bullets, my measured pressure with H4350 was 56.6 KPSI and my MV out of a 24" barrel was 2864 FPS, right in line with what QL predicted.
Last fall, my 16 YO granddaughter took it elk hunting, carrying 139 grain bullets loaded to 2800 FPS. She loved it. I think she didn't want to bring it home.
Just to be clear: The chart does not suggest that you take pressures up to 65 KPSI. That's just to show that if you're one of the guys that is running your 280 at over 3000 FPS, you're probably also running excessive pressure.
