Disclaimer: I've never run a pure sniping build
I'm confused. You didn't pick up Snipe, Sharpshooter or Shooting Spree? Those seem like the foundation for snipers to me.
Your crafting needs a huge pump. If you don't already know, most of your stealth skill is going to come from items that you craft. You'll want tailoring at 130 at least I think. Some for mechanics if you want to maximize damage with your rifle.
Drop psychosis, not worth it, especially with new innervate system. I'd pick up Gun Nut along with other three feats mentioned.