Indeed, independent submissions cannot normally create new registries. That's OK, though, because you don't actually need them. The purpose of the independently-submitted information document would be to document the existing protocol, both for the benefit of the community already using it and as a starting point for standardization work. Such a document can simply list the code points already used or reserved (the tables already in your draft) and need not actually create any registries. The registry creation can wait for publication of the eventual IETF-stream document.
-- Jeff