I'm not sure the poll page works. Maybe it's just me. I wouldn't want a sleeper only car. I want to sit up and read or watch the scenery some of the time. Couch or chair that converts to a bed. No bathroom, just the ability to pull over when necessary.

Like you mentioned, a public toilet is no one's first choice. I'd add to that that a compact RV style public toilet is even less desirable. It would be much easier to let cars run at 120mph to shorten these 8h trips to 4h or to simply use public toilets.