One of the reasons that we decided to drive a car through Europe is that we wanted to go camping some of the time. We wanted to go camping to save money (even with our impossible budget of $100 it works out to $6000 just for the daily expenses that have not been prepaid.) and more of the local european tourists on vacation camp for us to meet. The biggest problem that we have run into was rain.
A summer rain is nice while walking around the city, it cools you off and you're basically dry as soon as it stops. The problem we have been having is that it is hard to put away a wet tent. The way that we have been getting around this is that there is a cloth flap that rolls out in our trunk to make sure there is nothing above it for when the top is down. We have been using this cloth shelf to let the tent dry out on as we drive. We camped 2 days when we went kayaking and it rained while we were leaving. We camped on the beach on the French Riviera and went to sleep to the ocean and woke up to the sound of rain. We camped outside Barcelona to no event and it rained as we arrived at our campsite in Florence. (Luckily we had not set the tent yet, so no problems.) With hostels they are usually very close to the city center so we have had to pay for parking all night which makes them more expensive but that is part of the price with camping and they give you a bus schedule or have a shuttle into town. The main reason we wanted to camp in Italy is to be outside the city center. We read to many times of things being stolen out of cars or the cars being stolen. One thing funny that I have noticed is that the campsites charge by tent so the families that we are camping around have these giant monster tents with subsections in each of the 3 corners and a covered area in the center. The camping centers that we have been to cater to our kind of traveling pretty well with laundry-mat and internet cafes.