I just own a camper van. In current state of affairs, heat is a solved problem with diesel. Air conditioning still does not have a viable solution, aside from shore power. You can't practically use electric for heating or anything really beyond powering the lights and the heater fan.
Most vans max out around 3kWth. I have seen people use a used Tesla battery, but only have seen one report.
I guess we are talking past each other. You seem to be expressing perfectly valid conclusions based on the current state of RVs, and I am thinking about what will be possible in the future when instead of a gas or diesel tank, some RVs will have a massive, massive, battery as current EVs do.
Most vans max out around 3kWth. I have seen people use a used Tesla battery, but only have seen one report.