I'd use a tickmark character added to the layout as layout text with a conditional format that changes to font size to make it appear and disappear. But to use the images, you can store them in global container fields and then use a calculation field:
If ( IsEmpty ( LocationMap ) ; EmptyCheckBoxGlobalField ; TickedCheckBoxGlobalField )
Clear the "do not evaluate if all referenced fields are empty" check box and select "Container" in the return type drop down.
Excellent advice yet again, many thanks Phil :)