Hi Bart
If you are open to third party options - to me looks like, your scenario may be very well addressed by InfoBurst - http://www.infosol.com/solutions/infoburst/
You can can cache the data and email the dashboard to users without BO user id - there are two modes by which you can send - in one they can connect back to the server for more data and filter within the dashboard; in the second mode, they can receive an offline version of the dashboard with embedded data requiring them no connectivity back to the server.
You can achieve this by either building universe on top of SQL Serevr and create WebI report. InfoBurst can cache data from WebI. You can alternatively write SQL directly on SQL Server and cache the data.
Let me know, if you have any questions.
Runali