heat causing problems inside RV

I'll be bringing it to an RV service center soon for another issue so I'll ask them about the interior issues. In my opinion, if PW sells RVs all over the country, they should be designed so that they can withstand the weather extremes where they sell them. In the Southwest deserts it gets very Hot in the summer and that does not mean that the bathroom caulking and formica panels should get ruined. I don't have an air conditioned RV garage so it has to stay in our driveway. Sorry, I'm a little frustrated. Thanks for your input......Don.