To clarify a bit further, am I incorrect that DragThing is still working under Mojave? No need to stall at Sierra, correct?
Also, Keyboard Maestro could easily do Trash empty for specific volumes and/or users (as could vanilla AppleScript/Automator). Let me know if you want to explore this further.
Thank you for clarifying why it’s more than just an icon on the Desktop. (: while I personally trained myself to never use the Trash as a maybe/maybe-not holding area, I know that millions of Mac users do, so it makes sense. (I can’t tell you how many times I’ve had to assist people whose disks appeared to have run out of space, simply because they’ve never emptied the trash in literally years.)
I should dig out my DT license and grab the last installer before it disappears; maybe it has some interesting tricks I’ve overlooked for not having appreciation for its banner features.