Well, you have to think about the scenario actually playing out in real life. Fighters would cut far less weight, and might not cut weight at all. And there would be a preagreed upon pay penalty structure. For example, there could be a fixed penalty scale that followed a linear trajectory up to 3% over a fighter's weight class. Let's use WW for example.
170lbs
3% over = 175.1
If a fighter comes in at 172, they're 39.22% of the way to the 175.1 and lose 39.22% of their purse if they fight. Anything up to 3% over, both fighters contractually MUST fight.
If they're over the 3% the following takes place:
- Fighter that misses loses 100% of their purse, and is contractually committed to compete if the fighter making weight wishes to proceed with the fight
- If the fight takes place, the fighter that makes weight would be competing for a possible win, whereas the fighter that missed would get a draw even if they "win" in the traditional sense.
- Keep in mind that the fighter that makes weight has the option to back out, yet the incentive of getting 100% of their opponent's pay would almost guarantee that they'd fight. Considering that the worst possible outcome for them would be a draw, it would be a good proposition for them to compete.
If you don't think the aforementioned system would provide a STRONG disincentive to game the system, your business acumen might be in dire need of reevaluation.