Hi n2slugs welcome to HW and the RA forum
I have AS also and it does affect my neck, although it doesnt hurt as bad as when it flares in my hips and lower back. The neck pain is almost like my neck cant hold up my head (hope that makes sense ) I never want it to get as bad as it does elsewhere as, like you, I am scared of what that will be like. So at the moment the pain is tolerable and I guess that its my meds making it that way. I have had occasions where I have been unable to turn a certain way where my head will seem to snap back to a more comfortable position, but I think that is when I have overdone doing something (again I hope that makes sense lol).
Keep posting to let us know how you are going.