Been reading up on the forums before posting, to make sure I'm not repeating previously asked questions. Some helpful posts that I found so far:
The last one had something which I am going to try implementing. Essentially, I can add map boards to a list or tabbed panel if they are under the 'charts' category (for whatever reason). I can change the name of the charts button to something more appropriate and this does in fact give me a scrollable list of different boards. As far as I know, it's still not easy to change ownership of different boards, but as long as players can keep track for themselves which heroes belong to which player it's not a big deal.
I've uploaded the latest version with a simple example of this function in place. I'll fully update it as soon as I finish building the actual hero cards for my physical playtest. Then, I'll try to learn more about the invisibility function and try to find a good way to make pieces visible/invisible in large numbers at once. Since I will in fact be using boards, rather than just placing pieces on cards, I may be able to automate some of the hit points or experience or something, but I'm not going to worry about that right now. The invisibility trait is my first priority (after finishing the boards).