How do we use SSO for both Windows AD and Trusted authentication?

We want to have the majority of our users access the BO 4 BI Launchpad using SSO with Windows AD authentication. We have set this up and it's working ok. We also have a subset of external users and need to configure SSO with Trusted authentication for their Enterprise accounts. Support says we can only have SSO for one authentication type. I'm assuming we can work around this by installing a 2nd Tomcat instance on our Linux server. Has anyone done this type of config successfully? Any other ideas would be greatly appreciated. Thanks!