I was here last night as a 42monk/whm, usaly was getting two of them before healing, just did checkra and cast regain and healing time was short. When i started getting around I-8 i could only do one at a time, but only took me down to orange with 50+mp to spear.
Level 50 me and my brother (PLD and DRK) teamed up on these guys. He ended up tanking. He didn't take too much damage, and Drain is like a Cure II but better, since it does damage as well.
I'm pretty sure you could, but maybe wait 2-4 levels for minimal downtime, especially alone.