I would like to build a 'real' sniper character for an upcoming game. I have built and used archers in several games who put out a lot of damage because they are taking a lot of shots. The concept here is stealth, shoot, stealth.
I need to pack a respectable (if not fantastic) amount of damage into a single shot each round.
Concept so far is gnome with swift as shadows alternate race trait with levels of fighter, ranger, and/or rogue. Fighter levels would (possibly) use the crossbowman archetype, ranger levels would use crossbow combat style, and rogue would (almost certainly) be sniper archetype.
I would like suggestions on feats, traits, etc that would help me approach the concept while still being a viable character.