I would not do it. There are all types of ways that people could overcome the age verification process. You will also have huge problems with interstate commerce and international commerce. The US Attorneys would crack down on you and close your business first and ask questions later. It simply is not worth even trying.
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.