I'll try to finish it in 7 weeks.

I did manage to finish it in 47 days. I'm attaching replays of some battles: passages through the Dragon, Arcata, and Phoenix lairs, as well as battles with the Human and Dwarf Heroes. The Orcs didn't have anything interesting to show, and when my Hero attacked the Demons, they were so underdeveloped that fighting them was much easier than fighting the neutral creatures surrounding them.

I think I could shave off another week from the result if, after the second Hero with the main forces reaches the top, I don't send him to follow the first Hero for support (because the main Hero is capable of handling most cities and outposts with a couple of dozen ranged units), but instead send him in the opposite direction, i.e., through another coastal outpost (the Dwarf one).
I have very good impressions of the map - excellent design and good layout, so a huge thank you to its author.
(The only thing that was tiring was the long sailing, because the loot you can get in naval battles is no longer that interesting - there's already an abundance of money and other resources, and spending five days just conquering territory is tedious).
I will definitely play it as the Demons and the Orcs when I have time (it's a pity you can't play as the Light Elves).