The front A/c is also a heat pump. Both are ducted in all ceiling vents. In hot weather the 13.5's struggle to keep up. Some things I did to help. Front windshield sunscreen. This keeps the heat out. The sunscreen inside helps but the outside one is much better. Also get one for the drivers window. Get them for the slide windows and door also. Awning on side windows. Turn air on early before it gets hot. Drop down screen on awning. I use a six foot but do a search on the topic. You can upgrade to 15's on both and you can get heat pumps on both. A heat pump is just running the a/c back words. Get a small floor fan to push air from cooler bedroom. In really hot weather mine don't totally keep up. I can cool around 15 degrees. So is 90 I can get it to 75 or so. Upgrading to 15's in Texas might be the way to go but in some CG's you might not be able to use both because of the amp draw. If and when mine die I will replace with 15's. Try the sunscreen. They work great.
Phil and Dianna
2011 Berkshire 390 RB