The no spot car washes do work. If you have bad bad water like Decatur Indiana, the only solution is a water softener.
Wash with their water and it will look like heavy salt deposits around crew heads crevices and on windows etc.
Around here we have lime in the water but not bad. I wash early of the morning, fast, and into the garage to towel dry.
Not able to do the Mh. They wash it inside though. I am going to put a whole house filter on the faucet where the hose connects though. We now have city water, the worse. If I find the where with all I'll put in a pump. Or grvity system since there are springs everywhere.
