I've been SR shaving about 4 months and have the same sideways & lay flat to the skin neck hairs. I've been experimenting for 2.5 months (of daily shaves), and am finally getting somewhere. Here's what's did the trick for me:
- 1 N-S pass with the razor angled a bit and the skin stretched toward the direction the tips of the hair point - but just until taught and not farther (overstretching was causing a LOT of razor burn for me).
- Clean up the valley alongside the trachea (if pass #1 was worse than usual) using a sything motion (which gets the tip moving "almost" horizontal).
- 1 S-N pass while pushing my trachea into the valley that's normally alongside it and stretching my skin the other direction. (I think stretching the skin "wrong" direction has more to do with getting the skin onto a different curvature of my neck than getting the hairs to stand up).

My neck still isn't BBS, but the stubble is short enough now that I don't feel it sticking into my shirt collar until evening.

I can get my neck smoother with another pass or two (DFS), but always get razor burn when I do. I'm hoping that in another few months my technique will have improved enough to allow the extra pass...

ps: I notice that I do better with both razor burn and smoothness if I wash off the lather and relather to do my neck. I'm slow enough that the lather has become stiffer (dryer), and it makes a difference. My total shaving time with lather prep, stropping, etc is ~ 25-30 minutes.