Moth.....For details on sites en route go to the ACSI website, listed below. There is a route planning option on this site.
http://www.eurocampings.co.uk/en/europe/
This website is excellent for planning routes and distances.
One point regarding your ferry crossing. If you leave Dover at around 8.00am it means you will not be on the move in Calais until around 11.00am (French time) and allowing for at least one refreshement stop before Paris means you will be on the Paris ring road (Parifique) at the start of rush hour. This is somewhere you don't want to be at the best of times!
I Suggest you get an earlier ferry, or one the night before and stay dockside in Calais for a few hours shut eye. If you clear Paris by 2/3.00pm then look for a campsite south of Paris. I did stay at one site which was about 30 miles south of Paris but it was terrible and a pain to get to so I won't recommend it.
However, further south on route to Spain we stayed at the following site that is very close to the motorway and would be ideal for your second night. This is:
Camping De Fondespierre:
A9 exit 28 direction Vendargues, turn right and follow signs to Castries. Take N110 from Castries and 800 metres past the village turn left towards 'Domaine de Fondespierre' and follow the signs.
This site is literally 5 minutes from the motorway so it is a good stop over. The pitches are tight but my van is a twin axle (8 metres long) and we managed to get on ok and there was no problem with it being a T/A.
The address is:
Camping De Fontespierre
277 Route de Fontmarie
34160 Castries
France
Tel: +33(0)4-67912003
www.campingfondespierre.com
email: pcomtat@free.fr
We used motorways all the way to Spain and they are great for getting from A to B quickly, loads of Stop off places (called Aires) every few miles. The tolls with a caravan are Cat2 but sometimes we were charged Cat3 (never found out why?) We did'nt add up all the toll costs but her with the purse said it was about 120 euros, one way. We returned via Bilbao/Portsmouth.
hope this helps, mal