I didn't say it because I didn't know for sure it was achievable, but I was planning never to rest with Nad
But it would take forever to get HLAs (I have them delayed until Level 21 at the earliest, which for a Fighter/Thief would mean 4.8m XP to hit Fighter 17/Thief 21)
Admit it, you're a masochist!
Whilst I can sort of understand delaying HLAs, I can't understand not resting. What do you do when he starts complaining about needing rest? Not spam resting* is cool, I don't understand an aversion to sleeping 8 hours a day (although personally it's usually six).
* For clarification I mean resting every time you get wounded, or just to recharge items.
Personally I wouldn't have considered changing classes before reaching level 9 Berserker; for one thing you get another enrage a day, more HP and better THACO. It would only take another 90K xp to get to 10th level thief over 8th level, which takes no time at all. In fact if you play BGT or Tutu and start in BG1 without an (expletive deleted) xp cap, you should be ready to roll as a Berserker/Rogue with all abilites available by the time you exit Chateau Irenicus. With the XP cap of course you'd need a total of 180K xp to complete the dual classing.