Hi Doog.
The first thing he will need is lots of love and affection!
We've always taken our dogs in the van, some from very young age, and not had a problem. Start as you mean to go on; if you don't want him on the seats, keep him off from the start. It's no good letting him up cos he's a baby, and trying to stop him later. That won't work.
Clive's suggestions are good, even though the cage might be a nuisance in the van. Out in the awning would be best, but not practical at this time of year. Try to get him into a routine, like putting him in the cage, in the same place at the same time every night. He'll then associate that with sleep, and you might get a full night's sleep!
Oh, and also be aware that the easiest way to fall out with your fellow caravanners is for the pup to be a nuisance on site!
I'm sure you'll soon get the hang of it. Just enjoy your new pup.