6 silent running it's impossible with skilled. 4 8 12 16 20 - you can take perks only on this lvls, and you cant take silent running on 4 lvl.
Every time you play in daylight(ingame) the perk ghost is useless.
If you trade ghost for sharpshooter you see 6 hexes farther and you see sneakers most probably more than 2 hexes. Every time you play in daylight(ingame) the perk is useless.