The ferry to Mazatlan is over night so it's suggested to get a Stateroom but reserve it ahead of time. Otherwise, you'll be sitting in a chair or sleeping on the floor. This also includes what you need to enter mainland Mexico from Baja.
From Baja Nomads
What you need
Have originals AND copies of
Credit Card for vehicle deposit
Be sure to know where to redeem your CREDIT CARD deposit when you leave Mexico
Reserve a Cabin
I would reserve ahead on line. We showed at the ferry terminal office the day before and no cabins available so we could only reserve seats in the salon. Not comfy for an overnighter. It seems they hold back the VIP cabin for any big shot that shows up late. Well after underway we bagged that cabin. Private baño with shower. Comfy!!
Bond runs 200-400 US, depending on the year of the vehicle. Putting it on a credit card is highly recommended because there have been instances where a cash bond was originally posted but when the holder of the permit goes to turn it back in, sometimes they don't have enough cash.