We farmed the hell out of her on our first play-through. Now she is way too powerful for us until we are at least level 52. She is level 54 and kicked our asses in about 3 minutes flat.
We did the same - used moonstone mostly to max out our ammo slots and carrying capacity. We both got the great legendary rocket launcher. I think we also got a legendary grenade mod that is killer - called Four Seasons.
We want more skins as well. This soon after release, I am not surprised at the dearth of heads & skins. With Valentines coming up, I know there will be a Moxxie DLC or at least some in game stuff like they did on Happy Mercenary Day which was super fun.
Are you familiar with the Golden Keys through Shift Codes? Probably, but if not, check out Gearbox's Twitter feed and get them there. They have given us some really awesome purple weapons, class mods, shields, grenade mods, and Oz kits. I am loving a little repeater I got from the chest. It is level 47. It has no elemental damage but it does over 2000 points of damage per hit and fires & reloads like lightning.
Oh, have you tried to get Skullsmasher yet from Nel? Do a search on Youtube. It was super hard, but totally worth it. Skullsmasher is one of the best snipers I have ever gotten. I love snipers ever since my first play-through of Borderlands 1 with Mordecai.
Have fun & happy butt-slamming!!