Hey, nice to see you here, and thanks for you kind feedback about the pod!
From what you’re saying, I’m not sure you need discrete priors – which would be way better, as dealing with discrete parameters is still way harder (that’s also why the Stan page you linked to focuses on continuous distributions).
It would be helpful if you shared the model here.
In any case, I encourage you to read the chapter about logistic regression in @aloctavodia’s book – seems like it’s really close to what you’re doing 
Hope this helps, and PyMCheers 