Well - he is very thin. I am curious though as to why his coat shines? The shine typically goes prior to the weight loss.
As far as the no hay in the stall - after they finish eating - there usually isn't. Not defending anyone - simply stating a fact.
Well, I looks like he doesn't have a coat shine, that different than simply the camera catching the light shining through the stall, that just mother nature and hard science, and the hay really should have enough for a stalled horse to graze on all day since horses stomachs are made to be constantly eating.
But anyway, to the original poster, I would suggest this;
get your camera set to time stamp your photos, all simple compact camera have it, if you don't know how and don't have the camera manual, just Google "how to set a time stamp on a [insert camera model and brand here]" it should come up. 1.
Take a picture with the time stamp 2.
Then take series of photos over time and print them as evidence that they are not
getting rehabilitated, this is solid proof because that time stamp on a camera usually is saved in the photos digital profile and can't be replicated so even if someone claims you put it on yourself, bring along a portable drive, sometimes called a thumb drive, a memory stick... idk what you call it but here's one:
save the pictures from your computer on them, so wherever you are showing these photos you can access the digital ones and put it in the computer and right click the photo to show properties, and it should be saved in the properties and that is not able to be edited. (NOTE: this will only work if your camera is set to the correct date itself) I would Google that as well if you can't figure it out. 3.
Contact a ASPCA, HSUS, or any local rescue, show them the photos, emailed or in person, both will show the time stamp directly on the photo.
Then you will have proof they are not caring for these animals. make sure to showcase the same animals over so they can't say they are different animals!
Hope I Helped!
Update up with any info.