Another option might be to have a paper tournament based on fish length rather than weight - this is what our club has done for years. The minimum length is 12" and fish are measured and then released. The points go up as the fish get bigger. If you are interested, I can send you the point counts.
Another option was one that I saw last week while another club was fishing a tournament on the same lake as ours. The had a weigh boat, when someone caught a fish, they put it in the livewell and raised a flag. The weigh boat came over, weighed the fish and let 'em go. Not real sure how all this worked, but it was interesting.