How to get around "Data sources from cross-tabular or historical type reports are not included in List or Chart gadget report data sources"

Per the page linked below "Data sources from cross-tabular or historical type reports are not included in List or Chart gadget report data sources". My interpretation of this is that a report for the dashboard must draw from a System View, not from a User View.

http://help.sagecrm.com/on_premise/en/7.3SP1/user/Content/User/IB_AddingNewDataSources.htm

Is this definitely the case, and if so, are there any workarounds?

An explanation of what I want to do: our Company records are linked to multiple users via an associative table. I want the users dashboard to show a list of those companies they're linked to. I have a report that does this (a custom report). But I can't get it to show in the dashboard.