Tina,
I would first of all buy a screw in restrainer, these screw into the ground and give a good anchor point. I put a permanent one in the awning,(which is where my dogs sleep, not in the caravan on the seats) I have another outside for daytime use, you can move the dogs bed to either, when it suits you.
START AS YOU MEAN TO CARRY ON, dont give a dog human attributes, it is the biggest mistake new owners make, an 8 week old puppy is fine on your lap in the van, but when she gets to be a boisterous teenager at around 6 months, and starts trying out her new teeth on the cushions/furnishings while you sleep, its going to be a pain trying to stop her,but if she has been taught that the van is your domain, and she sleeps in the awning, then you wont finish up with a wrecked van while you sleep,shes going to cry for a couple of nights and its really going to tug your heart strings, but persevere and she will treat the awning as hers and be quite happy,it can help if you put a warm hotwater bottle in the bed and also a clock, the ticking feels like a heart beat and can help to settle pups at bed time.
I dont know where you got your pup and what instructions you were given, but an 8week old puppy should have four meals a day two milk and rusk or ready brek, and two meat, at twelve weeks this is reduced to three, one milky two meat, at 6months you feed twice a day one milk and one meat until twelve months when she will get one a day. I would advise that you feed a calcium supplement on meals until about two years this will aid with the incredibaly fast bone growth.
Sorry for wafling on and good luck with the pup.
TONY A