Thanks, all. I have Illustrator, but don't 'do' Vectors and doubt they'd consider a test submission of three silhouettes, though I agree they'd be more useful as Vectors. I'm sure a designer would have a far better chance of being able to make the image a Vector than I would have.
Problem with taking the actual photo was a totally glary white sky, meaning I have to whack in tons of shadow fill, but even worse, the purple fringing in the photos are horrendous.
If they wanted to check I'd taken the original photo, I guess they could compare the camera number in the EXIF of the silhouette with those on all my submissions of the past two years.
I guess the only option is Alamy - 1 person, no MR, computer manipulation, isolated. I wouldn't expect these to sell on Alamy, but you've gotta do what you've gotta do.
Now to work on my isolations

Tx again.