A query on behalf of an acquaintance.

They're interested in the possibility of hiring a Routemaster to
transport people from A-B, not a great distance but the most sensible
route would involve a stretch on a motorway.

If a Routemaster is going to be hired, it has to have an open-platform,
not a door.

The obvious question is whether any bus hire operation would be happy
carrying passengers on an open-platformed Routemaster along a motorway?
Said passengers would not (yet) be inebriated, and could be trusted to
obey instructions to stay away from the stairs.

A rope or bar across the platform would be acceptable - like on this bus
(though AFAICS it's passenger-less):
https://www.flickr.com/photos/29520195@N08/8677999177

BTW, this is very much a preliminary inquiry - no research has yet been
done - thanks for any pointers though!