After some consideration, I want to drop the "modules/new sequences" part of my suggestion and focus solely on camps, and non-solitary effort in general. "Struggle alone in front of your computer" seems valuably different from "struggle alongside others in person."

One idea, off the top of my head: a household whose housemates come together specifically for the purpose of immersing themselves in math as part of daily tasks. Which I suppose would require at least one "teacher" housemate, who could live for reduced or free rent in exchange for enabling a math-immersive atmosphere (challenges, etc). I don't know if having no endpoint (as with a camp) is beneficial or not in this case.