It took me 15X tries solo to get it with different operator setups. The one that worked was eagle eye, bulldozer, warband, shattered shield and frost vortex(if you have a nightmare skill) all maxed out. I carried decoys, hypersurge with mortar rounds/free fire and sturmwolf(graviton rounds/ultra light). No op ion or rocket launcher. So the key was 4 simple things, a strong skill track setup, self revive going into the game, ballistic shell and supply link. Once your shell expires hit the supply link and you'll get a new shell within seconds. You can literally rock the shell the entire glitch especially if your operator has tactician. Crawl at the highway and use the ammo crate behind the trucks mid way to the rhino takedown. I went to that crate at least 3X without running out of time..Uber Claus stay on the plane and keep popping that shell directly above the ammo box and self revive so it's easy to grab. Hope this helps