Clocking aircraft heights is a very inexact science. Are you able to provide proof that the mentioned A/C were at 300ft and 30ft? If you could provide a photograph of the a/c with e.g. a tree in the background you may have some evidence, after verification of location.
Would like to point out however, that in a past life my job was low flying. Did it for 12 years. Unless one is current and experienced in the art of low flying, don't do it. You will come to grief. Yes it can be a lot of fun but it can only be carried out, with any degree of safety, after proper training and hours and hours of practice.