Wouldn't have to stop for RETB token exchange, or can they collect a long section from Arrochar to Crianlarich?
I believe that in the absence of conflicting southbound traffic (there normally isn’t any unless the Oban-Glasgow Sprinter, which the sleeper normally passes at Arrochar, is running late), a long section token can be issued from Arrochar to Crianlarich.
The sleeper, whenever I’ve used it, has tended to stop at Ardlui more often than not, usually to pick up some walkers in the seated coach. How typical this is I don’t know. I think from the times I’ve used the Fort William section, the Roy Bridge stop is made about 50% of the time.