They are easier to separate for me with a wooden cage. I plop one down and try to get the high lvl one in and once thats in and trapped, i can kill the others. Leave aggro range and come back and its ready to go.

I use a campfire and burn myself down low hp to activate it. It screams and heals me and i can open the cage, feed, close the gate. Rinse and repeat easy peasy.

Use the extended hud setting in your clickwheel it helps with figuring out your hp levels