What is necessary for a rogue to be able to snipe with a ranged attack? Can he spend 1 action to duck behind the rock he is standing near and make a hide roll, then strike with his bow as his next action and get a sneak attack? I also don't see any requirements for being within 30 feet in sneak attack.
If I am interpreting this right, it seems like it makes sniper rogues fairly viable. Their rate of fire would be cut in half, but they would get more damage per shot. Also, some percentage of their shots wouldn't be sneak attacks if they fail their secret hide check.
The only requirement is that the target must be flat-footed. And yes, this can be achieved by hiding from it.
Other options include attacking frightened foes with the Dread Striker feat or using Instant Opening.
I think it probably works best if you have someone in the party who can easily make targets flat-footed like a dueling fighter or any grappling character.