Following support replies given to others, I managed to make the slide-out navigation the main navigation for the desktop site. It is now to the far right of site logo and name in the header area. (That involved creating the menu, turning it on via the Activating Slide-out Navigation instructions, and then creating a menu called *empty_menu* for the primary navigation.)
I would like the burger menu to be visible *beneath* the header in table and smartphone views but — and I am completely stumped here — the menu simply disappears completely in those views!
Any idea what wrong switch I flipped to make that mess or how I can correct it??