Article 18, Section 1 says, "All package cars and tractors will be maintained in a clean and sanitary condition including mirrors and windows."
After I park my line of package cars and squeeze them close, I squeegee all the outside windshields with plain water from a squirt bottle every night. Works fine and takes less than a minute per car.
Once a week I do the inside windshields. Again, plain water, less than a minute, works fine.
Even though the spray bottle just contains plain water, since it isn't the original container with the original label, a blank generic label must be affixed with the word "water" written in, and zeros entered in the little hazard boxes. Sometimes I also write "H2O" so the Keter guy will get a woody.