Allow User fields in CoPilot

I have been creating some great emails via Co-Pilot, but our Legal Department requires a specific signature from our CSMs for external emails.  It would be great if in the Power List creation, I was able to grab User fields specific to account owners, or CSMs.  I can do cross object lookups via SFDC email templates, but am running into limitations in CoPilot.  I can create fields on the Customer Info object for CSM phone number and CSM title that are formulas from the user object, but with SFDC audits I would prefer not to create fields for the sake of putting a signature in an email.  Any help is appreciated!
Thanks for sharing this idea! 

Do you want to pick the signature of the CSM from here instead?
Thank you!  We are using HTML email templates, so this is not possible.