I believe, from what we have experienced an what many have posted here and elsewhere, of various electrical problems that minor or not so minor corrosion is a major culprit in our RVs.
We have stored ours indoors dry and warm for many years and since then no electrical problems, that I remember. Thermostats, control boards, fuses, plus vermin. Before then the thermostat was a headache for a long while. Points just like an old car ignition and just a bit of moisture, especially when it is warm/hot and humid stored outside. A dehumidifier would be a sound investment, I believe.
Notice all the moisture on the glass and everywhere inside in winter especially when it is wet. I don't know if they integrate dehumidifiers in the new coaches or not but it would be a good selling point, to experienced RVers I think.