Thanks for the reply. My general feeling is that having multi-polygons with only outer members (https://www.openstreetmap.org/relation/15912390) (https://www.openstreetmap.org/relation/13951181) achieves very little and makes it more difficult for other editors. Entangling too much geometry into relations creates a burden down the line in my experience. 

In the interest of having a more concrete discussion, I've submitted my preferred way to map things like this and would appreciate it if you could take a look and let me know if you think any nuance is lost. If I've damaged things then I can revert and will have learned something interesting.

https://www.openstreetmap.org/changeset/136948759

Thanks!