Back in the 60s and 70s people like Magic Bus, Top Deck Travel, Globetrotters used to do it hard with converted double deckers going into Russia, Europe, even as far as Nepal and India with onward flights to Aus and NZ. Slowly but surely they changed over to coaches and camping or staying in cheap hotels.
I read a story a few years ago about one of the German tours where they had three heart attack victims (fatal) on the tour into North Africa. I think the bodies were kept in their sleeping compartments until something could be done about it.