Whatever you decide to do, you and you OH need to be a 'united force' for any rules. So you really do need to discuss how something is going to work and what strategies you are going to use and support each other and follow through with them.
Personally I would set a time limit to finish a meal - something reasonable, 30 mins or so and make it clear that if you haven't eaten your dinner by then, meal time will be over. 30 mins is still long enough to eat slowly and not scoff the food down. Just my opinion.