Exactly what I'm playing.Any chance you could give some pointers on what stats / perks are good for the stealth sniper build? I've been playing with a similar build but have been really struggling at times.
Core perks should be Rifleman, Lockpicking, Gun Smith, Armorer, Ninja, Critical Banker and Better Criticals. That allows you to one shot one or two people from stealth and kill any tougher enemies with critical headshots (if you use the critical it's a GUARANTEED hit, even if you only have a 1% hit chance in VATS), or when in a pinch. Saved me countless times. Lone Wanderer is really great as well, if you don't mind being alone / with the dog (in that case attack dog is good). I think it breaks immersion so I venture alone. I would keep a shot gun as secondary weapon, since sniper rifles are far too slow to deal with multiple enemies up close. Lasty, "Sneak" is certainly something to look into, I'm not sure if it makes a difference tho. I play on Survival and enemies know I'm in the building 2 stories below me when I move one step, lol. they are just "alerted" tho, I still get the sneak hit when I hit them.
Defensively, apart from Lone Wanderer I actually have not a single thing invested into it. If I would, Life Giver would be the top priority followed by Toughness.
As for the success, it's a bit rough in the beginning, but soon you will one-shot everything - even legendaries. I think apart from Deathclaws, nothing has survived a critical headshot. Combine that with the extra sneak damage, and I think even those would be a one shot. Shotgun with "long barrel" is also VERY nice to use in buildings and the like.
edit: Some extra tips.
-Press regularly VATS while exploring. You get to see enemies you don't really notice otherwise. If it finds someone, leave it and snipe away manually.
-Use a Medium Scope rather then a "Long Scope". Feels way more natural.
-Enhance both of your arm armors with "stabilize" - makes a difference like day and night.
-Buy/loot modified weapons just to dispatch their modifiers, you can find stuff you wouldn't normally able to produce (yet) this way.