Multi-tenancy while on a private network

[abundren]

Hello,
I was wondering about utilizing a multi-tenant functionality when reporting and monitoring bandwidth utilization. We currently use the reports to bill customers, but would like to allow them to see their utilization in real time with a unique log-in. The challenge is that our system is on a private network. Is there a way to get around this without making the system which we use to monitor public?
Thank you in advance for your help.