Use business API to get membership for all namespaces

I want to export a list of namespaces, groups and namespace/folder membership using the business API.  Namespace and groups are fairly easy, but I'm struggling to see how to get the listing of folder membership.

 

I can see that the the list_folder_members endpoint gives me the info I want, but the problem with this is that it's scoped to a particular user and I want to get all namespace membership for all namespaces, which means I have to have a "user account" which can access all folders.  If a user doesn't have read access to the folder I'm querying (these are discovered using the business API and an admin app) then I'll get a "permission denied" error.

 

Am I missing something obvious here?  Or do I just need to ensure that there's a suitable user account which can be used to access all folders?