So I tried the PL-VD thing again, and I think I had a bad first impression... Something about the range to the dummy was causing it to not build stacks, so I never realized that you could continue to use other abilities while it channeled and then come back to activate it. Once I fixed that (stood in melee range), the damage and mechanics were much better. That being said, I still didn't like it as much. The rotation was wonky for me, always seemed to leave like a 2-3 second gap so I wasn't getting the PL-VD off on cooldown, or was skipping around to fill in the gaps making the rotation kind of random or inconsistent. Nothing wrong with that if it's your playstyle (by "your" I mean anyone's) but it's definitely not mine. Plus the overall damage I was getting was a good 400-500 DPS short of my other build.
Chaos/Rifle does sound interesting. I do keep thinking there's probably some merit to working out a non-traditional Solo/Tank build with the Vulnerabilities now... Chaos/Rifle, or maybe Pistol/Sword or Pistol/Hammer. I'll keep looking into those a bit, too.
As for an AOE ability, my go-to has been Shellshocker, but that's an elite so maybe doesn't do you much good in that build. But the reasoning for it is three-fold... First, it does just monster damage, AOE or single-target. So much so, that I'm using it in a couple builds without even taking advantage of the Vulnerability and not noticing any real drop off in DPS. Second, the longer channel seems to help my rotation... it ends up being pretty much spot-on, so I use it on every cooldown with almost no downtime, and the rest of the rotation is the same so I don't have to improvise anything to fill in gaps. Third, and this is key, it has a long hinder. Combined with my Signet of Detainment (only using a blue, but obviously purple would be slightly better) it's enough to let me spam Conditional Force 5-6 times whenever I use it. That's a lot of AOE. That long hinder also means that if you just go straight builder x5 and then Transfuse Anima, you'll get the bonus leach every time. That leech, plus Thirst, has been good enough for me to largely abandon using Anima Shot or Anima Burst as my builder and replace it with a builder that either does a lot more damage and builds for both weapons (like Safety Off) or an AOE (usually either Suppressing Fire if I'm doing Frenzy stuff, or Arc Flash if I'm doing Chain stuff).
So maybe you can use the same "tactic" -- something like Tactical Retreat or Coldwave (or both) at the end of your builder cycle, followed by as many Conditional Force hits as you can get (and maybe a Transfuse Anima at the start or in the middle just to get the leech). They both are doing AOE damage on their own as well. I'm using Seal the Deal in that set up and I'm not sure that it would be anywhere close to as good without it. Oh, the other bit is that I frequently use Pop Shot with Rocket Science in that sort of build just for the extra and frequent AOE option. There's so much "extraneous" AOE in that build that I tend to just use it all up on groups and rarely need any mop up. There's likely some other ways to get the hinder going (maybe signet or passive I haven't looked at?) to make it work as well.