Recommended way to manage a group of accounts that need separate billing

A group of accounts needs some kind of central management (via a single pane of glass if possible). The usual way to do this is to use AWS Organizations which allows the management account to federate into the individual accounts. However, separate billing isn't possible, as consolidated billing cannot be disabled when using AWS Organizations.

Are there alternatives (via 3rd party products, or otherwise) to do this? If this is not possible, are there other recommendations on how to do this--for example account federation, or creating an IAM user (with read-only permissions) for performing the audits?