Ugh....how I wish my neck hairs grew straight down....anyway I finally figured out against grain shaving there. I used a butter knife to practice a bit and after the initial up and down strokes I put the razor in opposite hand and made a down stroke towards the opposite side.

So right side neck: left hand, start at chin, down but curve towards middle of neck. No cuts, did fine. Ditto for left side neck: right hand, start at chin, down but curve towards left shoulder.

Right neck baby bottom smooth, left neck close but not perfect. Practice will continue.