I think the solution for now is to forget the charity angle and make everything 100% free with unlimited streams and no ability for pay-what-you-want.
It says I have 200 free downloads, which resets every month. Given that I plan for a battle every 6 weeks, I think that should be plenty for a community this size . . . right?
I have no clue. It sounds like plenty to me, but I’ve never attempted to organize or considered the logistics for something like this and I’m not familiar enough with bandcamp to know what to expect.
I know that in other genre type battles more people listen than participate but have no idea how that impacts downloads. I also know that this website gets a lot of traffic which is not registered users and I don’t know how that impacts play totals or downloads, but for a community this size and speaking of members who can be accounted for, then theoretically everything should be nice and predictable like most of life 
I’m hoping everyone will stream and no one will download. Maybe I’ll also post a G drive with all the songs on the judgment page along with the stream.
It would be really cool if this would work and I appreciate the work that has been put into it. 
I did not vote because I had no insight in what would work, that does not mean I’m not interested.