It took a bit of doing, but I found it, and it worked fine.
Apparently, the configuration editor does not install in the list of menu items by default. I had to go to the '+ add to panel' window (right click on a blank space on the panel), select the 'Main Menu' (Gnome Main Menu) applet and add it to the panel, then click on that, and select 'system > preferences > Main Menu.
A dialog box opened in which I found the configuration editor listed under 'system tools'. Once I checked the box next to that, the configuration editor appeared on the Main Menu panel applet under 'system tools', and I was able to follow your recommended path (configuration-editor > apps > nautilus > desktop > check trash_icon_visible) and set the trashcan to appear.
Thank you so much. I will mark this issue as solved.