Did you ask your friend and grandmother about what they thought about using a tennis racket? You might be ok with it, but they're the ones that would have to use it.I think the tennis racket is a great idea and we’ll try that.
If you can do any DIY, some PVC feeder and waterer designs can be filled from up top and would not require the opening of a cage/other secured area. So like if you wire off an area in the coop as you mentioned, the top of the pipe would stick up out of the wired area, and food and water could be delivered without any need to open the cage.It’s a big walk in coop area and in the corner there is an 8’x4’ brooder room with wire on the sides and I might just keep him in that while I’m away on trips if he doesn’t get better and figure out some kind of water and food system that doesn’t require anyone to go in with him.