Ah, I love the Marines! Up until he had to redeploy back to Iraq we had a Marine Sergeant join our group from time to time. He is a very good player.
He just couldn't understand how he kept getting sniped by an old man. Then someone told him my background and it was game on.
Of course you can play as a sniper in woodsball. Usually in my experience I will not remain in that role for the entire game, but this depends on the course layout. However, I almost always start out in that mode.
The two secrets I use; economy of motion and one shot. It is almost impossible for the human senses to determine where 1 shot has come from when concealed and there is at least a moderate distance to target.