Have you heard about the new CBP Roam app for your smart phone?
The app allows traveler to submit their required information to Customs & Border Protection (CBP) to fulfill US entry reporting requirements when traveling by boat back from Mexico. This cool new App which I ran across at the California Yacht Brokers Association CYBA educational seminar in San Diego makes it simple and quick to come back from Mexico on your boat.
Please download all your information prior to using it the first time. Takes about an hour. When you are coming back into San Diego you can upload photos of all your passports and travel documents. Then CBP will do a video conference with you and maybe give you clearance to keep traveling North. Pretty sure you need to be US citizens for this to work right now.