You bring up a good point about the admin.

Currently we have a request listener. If you are in the context of the admin then it sets the correct basepath to load from based on a user select, which is stored in the session. This makes sense when there is only one basepath but not so much when there can be multiple ones.

In terms of the issue with the admin I guess since we are using simple cms style setup where there isnt a separate route basepath and menu basepath this isnt really an issue. We have a listener that determines which menu tree to load for the current website but we've removed administration routes separately (it happens by managing pages or by inserting new redirect routes in the cms tree).

I don't think this is necessarily helpful to you as its specific to a simple cms style implementation.

For the sandbox style cmf where routes are stored in a separate location is it possible to just load all routes from all basepaths? Perhaps have a filter that allows you to choose a basepath and only see those routes?