I'm using maps of maps of maps since it's fewer lines of code.  The doc ends up looking like e.g.

```js
{
    "_id": "_local/mrviews", 
    "_rev": "7-b2cd1c7f18750f29cdd69188e99aa41f", 
    "views": {
        "bar/byId": {
            "testdb-mrview-aa43476dc0696564dc0697a2e03aaafb": true
        }, 
        "foo/byField": {
            "testdb-mrview-4accd7531db7d33c77ca931609faefec": true
        }, 
        "foo/byId": {
            "testdb-mrview-aa43476dc0696564dc0697a2e03aaafb": true
        }
    }
}
```