I did a two-person run once, and will wait to do a solo run until the 6.0.0 patch. A human druid, cleric, sorcerer or any combination of those, with augmented summoning. Playing solo doesn't mean you can't and/or shouldn't summon crits to support you. All sorts of Charm spells are great as well. Chaotic Good with Scather is more like a cheat, and isn't really necessary unless you plan to take on Iuz. As for Moathouse difficulties, I wouldn't go there until it's necessary. If you take time to do the many quests in Hommlet the single chara should level to 4 or even 5 before you leave.