[TwoHandedSword]

From what I remember hearing at the official PoR:RoMD forum (which, sadly, was closed down over a year ago) running two characters will get you almost all the way to the multilevel cap by the end of the game, especially if one of them employs rogue skills to gather extra XP.

I've completed the game solo, and found that I'd maxed out somewhere near the end of the Elven catacombs. So this time around, I'm soloing only through the Dwarven Dungeons, then adding Faeril as soon as I can.