This is a quest horde can do - but the questgiver is in Darnassus! Help came from our 66 Druid friend Ddori, who stealthed in and got the quest to share with us.
We did the quest by running in, tossing a couple target dummies each to get to the broken bridge. Since the mobs can't jump onto the bridge, they reset and we get out of combat. To get to Thaelrid, we drank Potions of Swiftness and activated our Gnomish Cloaking devices and made a beeline.
We originally intended to just die at Thaelrid, but we found surviving so easy that we decided to make it back to the bridge. The only time either of us came close to dying was when I tried my Gnomish Net-o-Matic and it backfired, ensnaring me for 20 seconds.