We support cases like this by using domain names as authentication. We plan to eventually support automatic spinning off of domains into their own account (e.g

We support cases like this by using domain names as authentication. We plan to eventually support automatic spinning off of domains into their own account (e.g., for your clients after you're finished with a project). But for now, they could set up their own account with their domain and it would just work for you as a dev. If you're curious: https://stadiamaps.com https://stadiamaps.com. Please email me at luke@stadiamaps.com if you're interested.