No new trackage or speed upgrades required. Terminal points would not have to be at convenient pedestrian locations, nor even provide ample secure parking. Schedule could start with very few widely-dispersed terminals. That won't happen, so let's start more modestly. There is a profitable RVrail operation in Mexico.
Passengers ride in their RV No diners.
RVs can run own generators or engines for climate control, lighting, accessories, entertainment. Establish an 800 phone and web site for info, reservations and ticket sales. Possibly use existing trailer-train type rolling stock for carriage of the RVs. Expand sales to conventional travel agents. Interline with other railroads inspired to try RVrail.