None of the rooftop units are that great.
Dropping the temperature 20-25 degrees from what's outside is about all they can do. And of course, it's a question of how much space there is to cool and how good the insulation is. A lot of the class-A rigs have two A/C units. My class-C has dual pane windows that helps some. But, we'll often partition off the (Ford) truck cab portion that has virtually no real insulation.
Alex
"There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge."
-- Isaac Asimov