Advice

One 15K unit should be enough to keep a 27' Class C cool. But there are a lot of considerations. One is how well the unit is built and insulated. The other being where you travel and ambient temps. General rule is anything 30' or more you need 2 ACs if you camp in hot weather. Our 26' class C only has one AC and we travel in some pretty hot weather and into FL during the summer. Stays cool. You will pick up road and engine/transmission heat while travelling, so running with the AC on while travelling in summer helps to minimize cooling the coach down when you get where you are going. Also things like insulated roof vent covers and black out shades make a world of difference.