Being rage starved has always been part of low level tanking. And nobody said the pulls have to always be clean.
As long as you have the main target, and pref the 2nd target on you and As long as the 3rd or 4th aren't on the healer it's not the end of the world. But also, as long as they are on you for the first 3-4 seconds you should have the ability to tank them all assuming you are using marks and your dps are not retarded.
Dungeon elites do not hit that hard until like lvl 40.
The best you can do is ask for 2-3 seconds on each pull, as long as you get the initial aggro you should be fine.
Also i believe that on nost, battle shout only applies threat on the initial application.