It is the employer's job to show that you did receive enough in tips -- not your job to prove that you didn't. And if you sue and win under the fair labor standards act (FLSA) you get attorney fees, so it is likely you can find an attorney who will want to work with you and your coworkers.
This reply is intended only as general information and does not constitute legal advice in any particular case. This reply does not create an attorney/client relationship.
You may find that the easiest way to resolve your problem is filing a complaint with the Idaho Department of Labor. Get as many affected workers as possible to file the same complaint. It is their job to investigate this type of claim and they can make the employer pay you, and fine the employer if necessary.