Have you considered the multi-instance option for CRMOnline?
"Multiple instances. Similar in the way that you can add user licenses or storage, you can also add instances to a Microsoft Dynamics CRM subscription. Each new instance that you add creates a separate and isolated Microsoft Dynamics CRM organization. This helps in maintaining distinct instances that are consistent with your organization’s unique needs, such as separate instances by department, location, or those to be used for pre-production and development. For more information"
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