Yes, as mentioned above, any meat that is slow cured or smoked long periods with low heat will need a curing salt/additive. Prague #1 is used for meats that are cured/smoked but will be cooked after curing...ie bacon. Prague #2 is used for meats that are air dried and will not be cooked after curing like salami. The chemical formulation is similar but #2 includes nitrites and nitrates if I remember correctly.
I do wild game sausage links that are cold smoked and cured overnight at very low temps. The Prague powder inhibits bacterial growth that could be extremely dangerous if not used in the proper proportions.
However, you say your pork belly is under refrigeration, and while this may be a game changer using Prague Powder, I am not sure. If you plan to slow smoke the bacon, that's where you run into trouble. I know you can buy "uncured" wieners that are not highly processed, but I think they are not smoked either.