A true CO-OP Networking enabled skyrim mod (in development), inspired by numerous comments online suggesting that this is not possible.
We have already developed a method allowing us to do so, which partially requires the presence of a C++ application running in the background (for networking support).
Because of some 'cheeky' steps required in achieving this goal, no compatibility with some systems is being advertised at this point, but we are working on this, and will work on this after release.
We don't currently have a reliable deadline, but this project should be finished around June - July, an earlier 'pre-release' is highly likely, but depends entirely on how busy my schedule will be.
If you are experienced with low-level C++ programming, or are an experienced Papyrus coder, feel free to open up an issue asking to be invited to the team. If you have any other way to help us, feel free to let me know at naclo3samuel@gmail.com, thanks!