Fax Pro - Set Outbound Trunk and Outbound Caller ID on a per fax-user basis

We would like to be able to choose an outbound trunk and to set the outgoing caller ID as a per-fax-user setting.

We have a few routes available to us, the cheaper routes are great for voice communication, but are a no-go for faxing. Additionally, each staff member has their own fax DID, which should be displayed when they send an outgoing fax.

My thought is, that if we could choose the trunk and the Caller ID on a per user basis, it would solve each of these problems.