Thanks everyone for the input so far! I have a lot to read up on and I will report back :-)
Duties and import fees are not an issue, but conversion fees are and if I end up with a high-class/high price RV that I can barely use than the effort might not be worth it. We'll be travelling mostly to Italy, Germany and France with the RV. We'll definitely stay at camp grounds, dry camping is not an option. I've been in Italy a lot many, many years ago as a kid, but I do not remember any sewer or power hook ups.