The Heroes Round Table

I am playing as Thane (Storm + Warfare), just got him into Epic and I love the character. I have a feeling that I'll be spending a tremendous amount of gold on re-skilling as I progress, too, but I don't mind since I enjoy the character so much.

So, after the six campaigns, what is there to do? Are custom maps only one mission long with no carry-over? Or is there some kind of mod out there that allows for army carry-over and additional gameplay?

(Not looking for multiplayer suggestions, purely single player.)