That sounds nuts, Shd.

I might give Impossible a go, but I think I would like to play on Hard as a Mage first.
I just finished my first game on Hard. I didn't have too much trouble with the 7 manifestations of Haas, but the final battle was tough. In fact, I had to reload an earlier save and assemble a team full of dragons. My strategy of using Phantom on my Horsemen etc just didn't work for the final battle. So my final team was something like:
14 Green Dragons
12 Red Dragons
9 Black Dragons (these guys are the best

)
130 Horsemen (I still love them)
14 Giants (cancels out the negative morale modifier for Green Dragons with a positive one of his own)
Even so I only had 8 Black Dragons and a few Horsemen left at the end. That final battle is tough, certainly it was the way I played it. I know that there are more efficient ways of playing, but my strategy was JUST good enough to finish the game on Hard. I say just good enough because I was really struggling to find enough money at the end. I must have wasted too much earlier on.
Here are my final statistics:
Hard Paladin
Level 29
49 days of game time
97 completed quests, 2 failed, 1 unfinished (the freaking find a Cyclops quest)
Leadership nearly 24,000
20 Attack, 22 Defense, 16 Intellect
464 Battles
427,000 enemy kills
37,000 my kills (better than a 10:1 ratio, nice

)
Score 890
I think I could score over 1000 easily with a Mage, especially seeing as you lose points for taking too long. I think about 40 game days should be enough to do everything. Also, I could have killed more enemies but I ran out of money. I think I could have got to level 30 fairly easily, which is interesting because I only took 1 level of the extra experience thingy.
I played this game solidly for eleven days to finish it. And when I say solidly, I mean at least 4 and sometimes as much as 7-8 hours a day. So I would say that it certainly took 70 hours of my life away. Game duration was apparently 50 hours, 49 minutes.
If you haven't bought this game yet and are thinking about getting it, don't delay any longer. This is enormously enjoyable and addictive. No sooner that I have finished I am wondering whether to start my Hard Mage game yet or not.