Accessing CRM data via linked server & SQL login

[MustangPriMe]

I'm trying to integrate CRM with a bespoke database on another server. I've setup the CRM server as a linked database, and need to query a table from the bespoke database with a Join on the CRM Accounts.
The linked server cannot connect to the CRM server using an AD login for various reasons. I'm therefore using a SQL login, the 'sa' user as a starting point.
What I'm finding is that using Microsoft's supported route of accessing the CRM data through the Filtered Views returns no rows, presumably because the 'sa' user is not a CRM user. Accessing the tables directly (e.g. AccountBase) is fine.

Is there any way of accessing the CRM data through the Filtered Views, from a linked server, which is using a SQL login on the CRM server?

Thanks
Paul