We spent 55 days in 50 different European campgrounds this summer . Record high temps were set in July. The RV,s that I saw were hooked up to power when they could get it but I saw very few A/C units if any. My guess is that they used fans to cool down at night. Most of the modern ones had solar.
There is no boon docking that I could see but there is dry camping and if the RV,s can,t get power dry camping or at campgrounds because all of the spots have been taken, they have to make their own or do without.
The campgrounds are very crowded and cramped and In 2 months, I never heard a generator.
Dave