Perhaps this is a well known fact, but perhaps it isn’t. Some areas can be entered before the main story takes you there. Due to a major brainfart, I once entered Opportunity long before I had to go there. This led to the level of that area being permanently set. I hardly got any XP at all once the main story took me there.
Perhaps this is something that could be exploited in this challenge? When you get to Three Horns Divide, you should be able to go directly to Three Horns Valley. And once you’re there, The Dust should also be accessible. The Dust will lead you to the Highlands, and from there you can, enter Opportunity, WEP and Thousand Cuts. Assuming these areas aren’t locked somehow.
Eridium Blight is locked early on, and I don’t know about Tundra Express.
More attempts will be made this weekend…
After getting past the loaders and into Bloodwing’s enclosure (following several respawns) JSJ finally made it to Bloodwing at level 14.5. After another handful of respawns he left with the Claptrap upgrade and also at level 15.5ish (killing Bloodwing- even if you don’t want to pull the trigger) nets a lot of XP. He was able to upgrade his shield prior to this by visiting Bloodshot Stronghold and Tundra Express- the vendors there still have gear in the 11-13 range (also, the Hyperion shotty he got from the gold chest was a Critical Crowdsourcing, not a Diversification- sorry about the mix up). One thing I’ve learned from all this is that sometimes you have to make a critical choice kill- that is, kill something so that you can advance and avoid either other enemies or a bad situation, and not just killing to get XP (better to make one kill and move on than to get swarmed, fail in FFL and start from the last respawn point). Also, this had given me a much better appreciation of Hyperion shotguns, which I generally tended to avoid in favor of Jakobs or Torgue (unless it’s a Butcher- I love a good parted elemental Butcher 
). JSJ will be off to find Brick later today…
He made like Zero by sneaking around to the back end and sniping FJ from one of the building pillars, at least until he ran towards the direction of one of the other needed voice samples. Had to clear out a handful of loaders that came after he fired off a flare- not something that FJ has usually lasted long enough to do… Headed towards the climb up Bunker Hill a few bars shy of level 17 so will most likely hit 18 by the time this part of the story arc is over- still hoping to head for Hero’s Pass at below level 19 but we’ll see. As for gear the Fridge and Overlook had vendors with gear around his level so finding stuff on level is still doable. Wish him luck- he’ll need it! 
With no singularity grenades to pull the AC so I could hit them in the back I was using a bouncing shock and then a bouncing fire grenade to try to whittle down their health. It worked to a degree but the absorb shield I had was simply no match for their damage output, so after several respawns JSJ went Sniper Sal. Unfortunately the only SR I had was the corrosive Barking Snider but hey, at least it provided splash damage. JSJ set up right at the front of the area where the save point was (learned that lesson after initially getting caught -repeatedly- while repawning at the elevator). It took a while but fortunately the AC kept close enough together that I was able to hit both of them with the splash from a single shot. Eventually they seperated and had to finish them off one at a time. By the time those 2 were dead the bandits had started to respawn themselves, which made dragging the last 2 AC to that point a bit tricky. tried to get a Goliath or to to rage on them but only succeeded in giving Hyperion more cash in respawn fees. Eventually though I got the last 2 AC and then it was on to break Boombringer. BTW, JSJ started this at nearly level 18 and finished at nearly level 20 because…