If you create say a report header tab, I usually create this as an annotation with a standard backgroud. It looks nice as is, however users have been asking to know when the report was last refreshed. I came up with a simple formula to give you the max date in the report. When I click on the annotation area the "F" for formula is not available. Can you please add the formula function to the annotation list. Therefore I could add a sinmple txt field to this screen with the last update of the report. A Content view will not suffice as it looks terible on the page and blocks out the standard background image. Please see my attached picture, as you can clearly see the F is not available.
I definitely recommend that you use the Content View, not only has does the Content view provide more options, but I don't see why you can't achieve the desired outcome using the Content view.
Note: You should be able to make Content view transparent by ticking "Transparent background" from "Tools > Toolbars and Styles" from Content view toolbar. By making the view transparent it should mean that background image gets shown.
If you are having problems trying to achieve the desired look and feel with Content View as opposed to Annotation can you post a screenshot + file with demonstrates the problem.