I have to hand the app off to my client so he can upload it to his account. I thought a wildcard would let us both keep the App ID in our Apple profiles. If that's not the case then maybe my question is more about how to manage an App ID I need to hand off to the client.
The App ID you specify in the Build Settings on the Project tab cannot include wildcards. The App ID you create for your mobile provisioning file in your Apple Developer account can contain wildcards. You will need to add your client's device identifier (a very long number in the "Devices" section of your apple dev account) to that mobile provisioning file to allow it to be installed on your client's device.