I had an idea when i was looking thru my pics.
Why not - for example - do like they have done on the 400th Embraer.
Put a little discreet logo on the 250k pic saying that this is the... 250k pic?!
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Photo © Johan Kellerman
Then use the same (but with diffrent numbers) logo for the 300k, 400k, 500k etc pics.
Maybe it's a bad idea, i dunno?!