@Whitney24 If you are willing to host people under 16 years without registration of them your solution might work. I am not sure if there are any unexpected ramifications with that process, however. I wonder if someone showed up with multiple teenagers and they were not registered and somehow caused damage if that would be claimable under your security deposit.
Maybe an alternative option would be to provide a refund on a case by case basis. That way you could have control on the savings to the guest and avoid abuse of the offer. What do you think? Just curious, but why do you want to do this?