Mark, our club is run almost totally on honesty. ie: if you say you caught a fish you did catch a fish. If you are unsure of a fishes id then do post a photo and the members will help you out on the id of your catch. Photos would be nice in reports just to spice things up a bit. There are no large prizes to win so anyone who (shall we say) exaggerates their catches is only fooling themselves.
The only comps we run that require a weigh in is (I believe) our Christmas flounder comp and that is a purely social event which again only offers a small hamper plus other bits and bobs as prizes.
When we used to run an annual open comp which was a little different as there were high value prizes which may have been tempting for some. Also non club members could enter so in this comp we were shall we say a little more careful on fairness