Anything can become a RIPE document, not just policies. The process is simple. Someone just says to the NCC “please publish this as a RIPE document”. And it is done.
For this case, I think we want something that reflects a consensus view of the WG. If you can produce an initial draft or outline and post it to the list, we can discuss that, make changes and go through a few iterations of the document. Hopefully we then end up with something that has broad acceptance from the WG. At that point, someone takes the finished article to the NCC and asks for it to become a RIPE document.
Over to you...