?Does anyone know what level I should be at before tackling this DLC? I tried at level 10 and got my butt handed to me!

Hmm... I'd wait until at least 30 but it depends on your kit and skill set...

Actually because of this, I tend to wait until much later than I normally would to go see the greybeards, since now finding out that you're a (not the) dragonborn leads to such complications...

Before going to Solstheim i would recommend you be atleast level 25, but it will still be challenging which is good.

Can be problematic if playing on the pc. I'm lvl 45 and having difficulty with Dawnguard due to a difficulty mod I'm using. During the main quest, the Keepers were capable of a one-shot kill, and did-so on numerous occasions.

lvl 24 here and im still haveing a ton of problems , i have a high armor rating with most of my armor and shield being FIRE resistant and i still get pumbled by the ash dudes. Its fun, but just make sure u save alot.