I think you need an additional role, namely an auditor. The auditor could come in periodically and verify that there was no cheating or corruption going on. Initially, the scale will not be such that anyone would be tempted to do something unethical, but if the price of a CRC increased enough, a Supplier might be tempted to bribe a Verifier to falsify their records. You mention that Verifiers might get paid less than they do with existing carbon markets, which may set up an incentive for corruption. One of the problems with the cap and trade market is the amount of credits given free to heavy industry by the governments running them. I think this is an example of the kind of corruption that must be kept out of your new market. Having an audit from a credible company would help to ensure transparency.