Level 50, like all multiples of 10, opens up a lot of new quests, some of which I can actually do. The runecloth turn-ins alone got me 40% of the way to level 51.
I managed to do a couple of difficult quests that had items I could only use while out-of-combat -- a bit tricky since I can't kill mobs, and I don't have a race/class ability like Vanish/Feign Death/Divine Intervention/Shadowmeld/mage Invisibility. However, as an engineer, I can use the Gnomish Cloaking Device, which does get me out of combat; well, usually...
The first was Scarlet Diversions, which by the comments on wowhead.com is pretty difficult for a player in his mid-50s, because it has a lot of mobs in one area with melee & ranged attacks, plus medic NPCs that heal everybody.
This quest is in two parts, even though the quest progress only has one completion (which ALSO caused some problems). You need to use Flame in a Bottle to burn the tent, and then plant a Scourge banner so the Scarlet Crusade will blame the Scourge.
I burned the tent the first time by just charging in a using the bottle before dying -- it acts like a spellcast, so it gets pushed back but continues during combat, instead of aborting. I saw the tent burn animation before releasing, but when I got back, then tent was back. I tried a couple more times using a target dummy, but even after doing it, I couldn't plant the Scourge banner because it said I was in combat.
I was ready to give up, but then (going by wowhead comments) I figured I could probably try the banner after I rezzed, if I could figure out how to get close enough without getting into combat. Mind Soothe didn't let me get close enough, so I decided to activate my Goblin Cloaking Device and run into the tent. It worked! I didn't even come out of cloaking when I started using the banner, which almost always happens when you try to do anything while cloaked. An invisibility potion probably would have worked too, since you can start planting the banner while invisible.
The other quest was All Along the Watchtowers, a quest Noor couldn't get to because the Alliance version has a killing prerequisite (the Horde prereq is Scarlet Diversions). Again, using a torch meant I had to be out of combat, and with ghouls outside and a (formerly elite) Skeletal Warlord inside each tower, that was a problem.
After a number of deaths, I hit on this tactic: die inside a tower and rez on the top of the broken steps inside (the warlord can't figure out how to get to me at the top steps, so I can buff up). Go down the steps and cast Shackle Undead on the warlord (until it takes; he's 6-7 levels higher than me). Then go near the door (still on the inside) and hope I go out-of-combat before the shackle fails so I can use the torch.
Eventually, I was able to do all the towers, but it was something of a grind. With some of the Redpath quests, I got to level 51, which means I can now do the AV battleground daily.