@Grubert — misery loves company! I got some help over at the BuddyPress support forum. This enables me to lose the sidebar on the BP and bbP pages, but I’m still struggling to invoke full-width display on those pages. This is being accomplished with some CSS “swapping,” which appears to be controlled by the catchbox_body_classes function in the Catch Box functions.php file. I just have to learn how to 1)override this function in my child theme’s functions.php file and 2)alter the code to invoke fullwidth classes when buddypress.php or bbpress.php are the template files.
Still working on it …