New to astrophotography this year but am moving along smile

I'd like to shoot NGC6960 in Ha and OIII with my ZWO ASI1600MM-Pro.
Still very new but I have a few targets under my belt with the Nikon 300 f/4 and 600 f/4.
The problem I have is, that while the framing at 300mm is perfect for what I am looking for, I'm afraid I will not be able to get the end result I want due to dithering, target misalignment, and camera rotation. Everything would have to be close to perfect to end up with the framing I'd like, and I'm not that good 

I have a Nikon 70-200 f/2.8 VR-II which I think would give me the room I need to get the final crop, but I haven't used it for astrophotography yet.

Any suggestions before I waste a (very scarce this spring/summer) clear night and find out the amazing in the day 70-200 is a loser at night?
Thanks!