What level for Everfrost to Qeynos?

[Baler]

first off shm+monk is a excellent duo.
second if you can't get through BB. Consider having your friend roll a barb shaman also (temporarily) to toss you heals while you fight mobs to get you high enough level ~8-12 to get through BB without dieing.
Then your friend can delete that shaman and you can both continue on from there.

I've seen people do it at level 5 and 6. Most don't make it at those levels unless they can strafe run well.
Learn the layout of the everfrost to BB tunnel,. There are rocks you can get stuck on and the gnoll guards will get ya!