Hi,
What about integrating the SwellRT · GitHub infrastructure in Cuba. With this we could have a clean collaborative solution.
Including GitHub - SwellRT/jetpad: Collaboration tool based on real-time text editing as a component, we would gain co-authoring with a richer editor (Headings …)
I wouldn’t mind it to be part of WebDAV so you get some extra intensive for the license 
Kind regards
Thierry