Buy a roll of insulated aluminum bubble wrap and wrap your exterior hoses with it. Keep the internal water at a slow, ongoing drip from the outside faucet as well as the interior faucets. You may also want to get some bales of hay and place them around the outside of your RV. This will keep the colder, blowing air from getting beneath your coach and will keep pipes from freezing. The heated, enclosed underbelly will help a lot with this. Also, you can cut the insulated foil to size and place it on all of your windows. This will really help to maintain a comfortable interior temperature. Make sure to cover ceiling vents with insulated covers as well. You can buy many of these products via my articles or go directly to Amazon for them. Your wastewater won't freeze in the tank but empty often as an added measure of protection. The pipes it travels through will be empty until you pull your tanks, so they shouldn't be a problem.