The closest precedent that I know of for this was on the steam-hauled freights around Wolsztyn in Poland in the mid-1990s, as pictured here -- I think enthusiasts really were the intended users, although the shunters also travelled in the coaches. They later reverted to ordinary vans -- maybe they found that most enthusiasts preferred to ride on the footplate.Put a coach behind the loco on all freight services that can be used by enthusiasts.