You cannot count on that so essentials need to be with you. If you plan on no more than can be carried in a backpack it allows you to enjoy moving around to enjoy all of the features of the ferry. Suggested items in backpack would include a Pactowl and shower supplies, snacks, non-tip cup, medicine, camera, and binoculars. Access to the car deck is limited and may not be possible during parts of the trip. The backpack is your survival gear while on the ferry.
Showers are free on the ferry.
This is the easiest time to freshen up during our travels. The cost is most difficult to estimate as there are still too many variables. Costs will be much better if we have more travelers to distribute the costs. Gasoline costs are unknown and the RV requires a lot of fuel. All travelers will share in the cost of land travel in Alaska.