Fortunately there are enough people who do think it's worth paying to travel behind steam or there'd be no steam to photograph!  Ideally the trip should be enhanced by a welcoming boarding experience (a chance for a leisurely inspection of the haulage, including in this case during the mid-point attachment perhaps?) as well as that onboard experience and being made to feel appreciated for keeping the show on the (iron) road.

 
Many moons ago, on 14th February 2009, as a 30-year long-service award, my company paid for myself and my wife to be pampered aboard a British Pullman dining experience behind Bulleid Merchant Navy Pacific, 35028 'Clan Line' (if I'd paid for it myself, I'd have needed a second mortgage!). You barely noticed that you were behind a steam locomotive!  The onboard experience was the attraction (I won't say the scenery - unless you enjoy the south London suburbs and Surrey Hills!).

Rather more recently, I treated my daughter (who is an avid Harry Potter fan) to a weekend around Glenfinnan. As part of that weekend, we boarded a Scotrail Class 156 unit and travelled from Fort William to Mallaig and back. We saw exactly the same scenery as the tourists on board The Jacobite at a (huge) fraction of the price. We witnessed The Jacobite cross the viaduct from a couple of lineside vantage points.

As an avid railway photographer, I would gladly phot a steam excursion from lineside, but as a participant of a railtour, it really does not matter what the motive power is.

 
https://www.railadvent.co.uk/2025/05/steam-locomotive-34046-braunton-to-pass-through-dawlish-this-saturday.html


[personal opinion piece] So that's about 4 hours behind a diesel, half an hour for a loco change, an hour and a quarter behind a steam engine on the main line, then a final section on a heritage line where you could travel behind a steam engine anyway.