Best way to manage current customers and prospects

Hi,

We are currently setting up our account, we have the Professional plan, and I have a question on best practices to use with our prospects. We have 7000+ active customers that our customer support team answers tickets to and I was planning to pull over our SFDC Accounts/Contacts to build an Organization/User for each account and contact within SFDC. Outside of those customers, our customer support team also answers questions that come from our prospects. I want our support reps to be able to view the SFDC data on these prospects but that would involve adding over 100,000 additional organization from our SFDC instance.

I haven't used Zendesk before so I don't know at what point there are an unmanageable number of organizations. Would pulling in all our SFDC prospects as Zendesk organizations be a wise use of the organization feature or is there a better way to provide assistance to these prospects?