Unless he has a lot less defense from his cloak of the grand vizier because he's in a party of two...
Why are all of the active Wolfgang players high-SP builds?
Unless @Waterbrick Down says otherwise, I think you can, but the battles would be a little hard for a level one. In my first quest, I was a level one in a party of heroes around level 20, and I wound up having to do things such as always target the lowest level enemy, distracting enemies whose free hits we didn't want, and helping the other heroes through non-typical methods (such as untangling the other heroes, but I doubt you'll be doing that.). I reccomend that if you do wind up signing up, you read a few quests with mixed levels, such as Missing Medusa and My Best Friend.