They like floating plants anyway, so that is a good solution. My HOB
filter pushes floating plants all over the tank. So I tie them with string or a very loose rubber band and attach it to a suction cup on the glass. Anacharis does well as a floating plant if your LFS
doesn't have a good selection of floaters. You could probably make a pretty good barrier with one bunch of anacharis. It will grow like a weed so close to the light.