You know that you'll always, and I mean always, suffer from the lack of preventative "medicine" that magic can provide. Having said that, potions are there to even the score. With a game like IWD, the makers knew that some players might want to play a thieves' party, out to plunder the forgotten keep of Dorn's. Or you may want to play pure fighters as members of a mercenary company stuck in the Ten-Towns area for the winter. Therefore, I don't think it's too unreasonable to assume that you can get through the game without any magic support. It'll be harder, or challenging in a different way that's all.
I like the fact that you've already got a
"scenario" to your character before you even put fingers to k/board or mouse. That says skills mate!
Anyway, as for character type, you could solo as a fighter for the first few levels, then dual as a thief. From posts I've read, cleric/rangers and other multi-classes are more preferable then single class or dual-class, but if you stick the game on Insane or HoF, you can have a few levels under your belt before you finish Dragon's Eye (mind I haven't tried soloing on HoF so you're on your own there). That's sort of my plan at the moment. I might dual to a thief, or go back and start again and dual to a druid. You know they rock!
In the end, it's what you really want to play. From the very description of the character you gave you obviously like the story element, so why let the mechanics of the game spoil it for you? Try it, and if it doesn't work, let me know quickly before I make a mess of it all.
