My experience from owning our Cav King Charles Spaniel for 4months now (BTW this is the only dog I have ever owned!!! So massive amounts of experience here)
1) she gets out and has a wee / walk whenever we stop, which is roughly every two hours anyway. I have spent a bit of time teaching/reinforcing this with her i.e. a reward for weeing, just as she gets at home for weeing outside. She travels in her bed. She wont wee in her bed, and I'm now pretty confident she wont wee in the car. She gets very restless when she needs to go to the loo, so if I don't stop its my fault anyway. I have also told the kids if she does start weeing in the car they are to pick her up and cuddle her very tightly so they get covered in wee, not the car. I can easily wash the kids change their clothes, the car is a bit harder to clean. They seem "happy" with this concept.
2) cant comment on the baited thing, but keeping them very close sounds like common sense to me.
3) She sleeps in the camper, this translates to sleeping in our bed most of the time! Just like home really.
4) During the day she comes with us, if we around the camper then she just hangs with us. Depending on where we are and how much traffic is around will dictate whether or not she gets tied up. We put a mat down or her bed down on the ground and she knows this is her spot, and generally spends most of the time sitting there anyway. When we first arrive she wants to investigate every where - presume that is normal, but once that is done she does not wonder far anyway.
5) Never been to national park with our dog, so cant comment. Did however stay in a hotel with her one night though!!