Your objective should be to make as much money as possible using realistic strategies. In OPEC, that means coming up with creative solutions to cooperation that would be workable in the REAL WORLD context of international competition. Cheesy workarounds that violate the spirit but not the letter of the rules I set out may help you to achieve the monetary objective, but will not provide you with usable lessons in a business context.
If you're uncertain about the legitimacy of a given practice, you should ask yourself whether whatever tactic you have in mind is at all sensible in the real world version of the environment being simulated. If it is not, then you should refrain from that practice. While your narrow goal is to make money, the broader pedagogical goal of the experiments is to give you the opportunity to try out various tactics and hone skills useful in the real world. Tricks that take advantage of the fact that it is a simulation, rather than reality, may net you a short-run monetary gain don't help you a bit in becoming a better strategist/tactician/negotiator/leader in the real world. Presumably the reason you took the class is to become a better leader and not to learn how to "game" a simulation.