You could do chapter-based threads, but ask posters to limit discussion to that week’s pages. Then when the next week’s reading starts (and you read the other half of the chapter) you could have a post in that same thread to announce that the next part of the chapter is now also fair game to discuss. An example:
I’m refraining from voting in the reading speed polls because I am probably not the target demographic and I don’t want to skew it.