Wait until level 50 or go with friends.
Get a corrosive weapon or 2 (helps if one of them is a sniper), abuse cover, etc.
I didn't try this mission on my mechro until after I'd activated 2.5. It is probably the toughest fight in the game I've had so far. My tips:
- Long range. I had a corrosive sniper and aimed for the arm joints of loaders. They're very easy to hit assuming your anarchy is low, do massive damage and stop the things from shooting at you. If they're far enough away they don't even fire back and you have a nice grace period to take shots while they walk towards you. They still fire the lightning orb from their eye, but that is easy to dodge.
- Herp derp in a box. The badass surveyors were a huge issue for me, they hurt so much. I found that one of the alcoves where engineers come running out of (the one closest to the cliff edge) to be a very safe area. You can crouch behind the railing to take cover and I think the surveyors will aim at your centre of mass when you're standing, causing their shots to harmlessly hit the fence. It also causes the jet loader to fly around in circles doing nothing until they get bored and go into bot mode to come into the alcove after you. Occasionally engineers will run out behind you, so I'd keep a heavy hitting close range weapon in both fire and corrosive equipped in case that happens. Eventually I did have to venture out to take care of the Constructors, but only after every surveyor was dead.
Ammo was a concern, so I'd recommend an absorb shield, although I didn't have one. I'd make a dash after every round to grab what bullets I could off the ground. Constructors drop a ton of them.
Sadly by the time I completed this and got the Cherie-amie, I had the Pimpernel from Scarlett DLC which totally outranked it. Cherie gets bonus points for being a Moxxi gun though, and also has healing. It's still a nice reward if you get an element you don't otherwise have.
i'm sure there are better strategies out there, but i spent almost all waves of all seven rounds hiding behind the large boxes on the landing platforms that overhangs the cliff.
from there, the vast majority of enemies will not aggro until you go find them. this means you can snipe all the loaders up on the ledges from complete safety.
a couple times (and i believe once is on round seven... wave four?), a cargo ship will unload a bunch of engineers on that platform. i just ran over to the elevator and dispatched them as quickly as possible before returning to the platform.
using this strategy, the hardest parts of round seven were the second and third waves.
wave two is the onslaught of jet loaders. you will be using your special ability A LOT; however, you want to focus on the repairbots, NOT the jet loaders... other than that, dodge missiles and pray. this was the wave i died on the most doing round seven (three times, i think).
wave three starts off with the two super badass loaders on the platform IMMEDIATELY in front of you... but the trick is that you ideally want to cripple them, not kill them. a third one shows up immediately after one of them has been killed, so you want to whittle BOTH of the originals down so that you can focus only on the third when he shows up... bear in mind that the ion shot from a super badass was able to wipe out the full shields and 40% of maya's health... and she was level 37. so even without arms, they are far from docile. anyway, if you can take down two of those super badass loaders, the rest is a cake walk.
it's a lot of rinse and repeat until the last wave. bear in mind that rpg loaders are arguably the most powerful enemies in playthrough one... namely because they can OHKO your character at pretty much any level, and they tend to come about 4 or 5 at a time in the ore chasm. that said, if you are on that platform, exactly zero of them should ever aggro until you go hunting, so you shouldn't ever have to face more than two at a time, and you should still have ample cover.
the last wave obviously poses a few tricks with the two constructors... but with a strong corrosive SMG i was able to take down the close one (again, behind my boxes on the platform) by sticking my head out long enough to hit him in the butt with a short burst before i got a face full of missiles. after that it's constructor business as usual: sniper rifle.
those should be the only tricky spots if you stay on that platform and snipe conservatively and efficiently... your only other problem might be running out of ammo. that may sound like a joke, but it's not... it happened to me once : /
also, bear in mind that this is what worked for me with maya... that said, since axton's turret tanks for you, that should help IMMENSELY with the jet loaders and super badass loaders. salvador is his own tank, and gunzerking should make short work of... everything. i only played around a little with gaige, so i don't know how she is at higher levels, but she should be able to just repeatedly throw out deathtrap and then defend herself.
which leave zero. if anyone can solo this with zero without being EXTREMELY overleveled (ie, 40+) and without twinking weapons, then that person is much better at this game than i am : )
without God, death is the only absolute