I think you've got no chance. Does it say Type S on the bag? That is already 2 parts cement, 1 part lime, and 9 parts sand. So your final mix is roughly 2 parts cement, 1 part lime, 20 parts pulp, 10 parts sand. That's roughly equivalent to 1/7/3. You know papercrete better than me, but I don't think it will set well.

The stucco is basically a ready mixed mortar. You can use it for projects that require a roughly 1:3 cement:sand ratio, possibly with other ingredients. Don't add more sand. You can add more cement and use it that way. For example, two bags of straight cement and one bag of Sakrete will give you a 50:50 cement sand mix.