Well, I'm an old duffer, so, I have a fold-up canvas seat for sitting on when waiting any length of time to take photographs, or, fishing, ideal for this purpose, you can sit near the platform edge and don't get in the way of anyone else standing behind you, simples......
And really, a station platform is private property belonging to Network Rail, or a TOC, it is not public property like the street, and therefore in accordance with the rules of the railway you don't have carte blanche over what you think you can do when on it, regardless of a Steam Special, or, the Royal Train coming through, as laid down in the regulations, if I was in charge, I'd make you all board a train, which is what you're supposed to be doing by standing on the platform, in essence, or, seeing someone off.
Cheerz. ex-railwayman.