I wonder how do you manage to pick the maps. Since patch 1.1 all the map guardians are immobile, and if they move by chance, they stop after a few squares and quickly return to their starting position.
EDIT: Interesting. I just managed to kite away the army guarding the Verona map on the Scarlet Wind island. One doesn't really need to kite them far - just a little, in order to sneak beside them and take the map. Weird. This is the only map guard enemy that allowed me to kite them. Bug?! Intentional, so that the player can get the map through skill and stealth?
In addition to that, on impossible, one must save money like crazy in the beginning and spend it only on the most important items - items that he/she will use for quite a while. There is no point in spending 10k on a +1def/+200 leadership helm if you're going to drop it after a few levels because you found a better one.
I strongly suggest tricking the Gromozeka, taking the amulet and going back to Debir. Doing that has a chance of spawning Paladins in the Mage tower. I know what you're going through, cause I have the same problem. I've cleaned up most of the starting islands by the beginning of day 2 and all I see now is overpowering and impossible enemies on Rusty Anchor island, because I can't get an army of the units I prefer and I'm forced to play with incomplete stacks. But there is always a way
The most important thing is to keep a cool head and do not give up.