I contacted the organizers of this trip. I asked about photo stops and run bys. This is their answer
"We will have photo stops and runbys and false starts during the trip within the operating constraints of the lines we will be running on. I have a meeting in Moscow in the next couple of weeks to discuss suitable locations.
Due to the huge distance to be covered, runbys will not be more than one or two per day. The train will stop every 100km or so for water or loco changes so there will be opportunities there for photos as well."
I still think that in this day in age it is remarkable to put together an all steam trip, using 21 different locomotives. Golden Eagle Luxury Trains have had a good working relationship with Russian Railways for years. Here is a taste of what you get.