hiding under the ramp room thingie for solo nightfall totally works, if you have a weapon that does armor piercing. It goes through the wall and hits him, and absolutely nothing hits you back if you are cowering under the sloped ramp. You have to do it this way solo, since if you try to hang out by the entrance ledge he never comes over there, and if you jump down to lure him he will rape you. For 2-3 ppl its fine since one person can snipe him from there while the other is bait, but for solo the armor piercing way is great.
it takes forever though, im doing it right now with ice breaker (to regen ammo) and final death, my sniper rifle with ammo piercing. If you nudge into the little ramp nothing hits you, and you just shoot at him through the holes above you. its like some weird pervy japanese hentai, all you see are people shitting above you through holes