Take damp towel at one end a take a wrap or two around a 4 foot lath. Use this to place the hanging towel between the cab and shell. Work it up and down and sideways until your have the best results.
Not sure how to get to the windows but use: 1 gal water, 6-8 caps full of vinegar, 2 drops of Dawn dish soap. Cleans hard water spots and dirt like magic.