Do yourself a favour and contact the CFI's at these schools. Explain the problem and ask that they don't continue to use your site as somewhere for PFL's.
Usually, many would assume that use of an airfield of any kind is less likely to lead to noise complaint problems and they also have no idea unless you tell them that such an issue may exist.
P.S. How short is your field? You'll be amazed how small a distance you need to get a light a/c down and stopped in if you do it right. If it's over 400m then it's no problem for anyone half competent in something like a cessna.
(May not be the same getting out again however!)