I soloed it 3 times today wih 3 different classes. I died once at that part with my warlock, not because of the snipers but because the monsters left alive teleported to where I was even before the 3 waves started. Weird as -blam!-. I think it was just a glitch, needs confirmation. I died 2 times because of the snipers one shotting me with my titans. Played very carefully on my third run and it went fine. Made a flawless run with my hunter. All in all, I just snipe/rocket the 3 waves behind the 2 boxes at the start of the bridge. There is really no need to go beyond that if you play carefully enough. Yes you'll be in the hobgoblins range but you can well deal with them if you crouch and take pot shots.