John,
I think the hazy look is likely due to moisture absorbtion into the finish. The changeover to water based finishes was not without its faults. It could be sun damage, but it would have to make sense that the sun hits the area of the cabinets that you are having problems with. There were years of Beaver coaches that had this problem, and I thought that it might be earlier than the year 2000, and by then this problem to a great extent was all worked out. I usually run air conditioning some when I store the coach at home, along the gulf coast when it is warm and humid to prevent this problem, as well as not induce mold issues. Once the milky finish issue appears, as far as I know, there is no way to eliminate it.
These coaches have what is equivalent to fine furiture in the form of the interior woodwork, and how you would treat fine cabinets in your home, climate wise, would be a rational guide. I have used some Johnson Pledge at times in the coach, but for the most part we just dust the surfaces from time to time with a lightly dampened cloth.
Later Ed