I got mine from Decathlon. They have a few different ones. Mine has a red light and two settings on the white light. It wasn't the most powerful one they had but it's pretty good when searching for horses in a pitch black field.
Mine isn't a cob, but a bit fitter put her in the NS tactio turtle top eggbutt. After a while she didn't want to open her mouth when bridling. I swapped her to a hanging cheek Myler with a ported barrel. She goes well in it and we dont have any problems putting her bridle on now.
If you blow them to the fence line just make sure you blow them far enough away that the horses can't get them. Otherwise you've just created an easy larder for them 🤣
Could you take Old Lady out throught the gate and feed her there? This is what we do with ours when we need to feed at the field. Then put the buckets in for the others either while she's eating or after she's back in the field.