Thanks Wayne,
I’m stuck between scales. My dad got me a Delton combination car & then a LGB mogul. That was the trigger that got me into trains. At the time, they looked okay together, and I probably was unaware that large scale was not standardised.
I mostly own 1:22.5 LGB and some 1:24 Delton and USA Train refers., BUT as Herself became involved, we now have a 1:20.3 Bachman and 1:20.3 AMS carriages x2 and for some reason one 1:32 modern UP “pretty” rail speeder.
My people are mainly Preiser. Some are reportedly 1:24 (cowboys & Indians) but most are 1:22.5, but I have some woodland scenic “G-scale”.
I suspect that as a rail truck travels by itself would not call attention to itself in a garden setting, but I think I would choose to avoid 1:29 to 1:32. So I guess to answer your question, I’d say 1:24 to 1:20.3 would be my aim. I’d prefer build something rugged enough to use in the garden.