You don't need other players for the protectorates.
Just carry the idol to a location you can use to your advantage, aka a higher vantage point etc... then get shot while still carrying the idol, hop away, and kill the player who was shooting you. Repeat 5 times. Protectorate in the pocket.
Of course this requires a little bit of skill, but because of the low health and amount of low levels to be found, it shouldn't be to much of a hassle. And unlike Uncharted 3, you get to use your primary weapon after you hop away from the idol.
Not too hard if you ask me, but I can't judge your skills. Oh and the lag shouldn't be too much of a problem. With the low health and such it's easy to kill em quickly.
Why did you deleted me? Did you changed your mind?
Just some trouble at home so I don't have access to my PS3 for a bit. Luckily I have a laptop I can use, and a Vita to play games on also. I will re-add you guys when I am able to, sorry for the inconveience, it all happened a little too fast.