Apologies that we're late to the conversation....
We have 2 dogs who are now 8 months and 3 and a half years old, Dana and Luna. They both travel in a crate each in the boot area of the camper, they're quite content being able to watch the passing traffic. Each crate is big enough for their bed and has a water bowl attached at the side. You can just make out the outline of the crates in the rear window -
The crates can be folded flat and sit in passenger footwell when parked up, stored in the awning or we often have ours stored in the roof space.
Our previous dogs were left loose and would lie on the bench seat or jump over the back when they wanted, they were 8 and 10 when we first got our camper, so we knew exactly how they would travel. We only once had an incident with the older dogs when we went across a cattle grid too quick, Poppy freaked out and somehow managed to get herself wedged between the handbrake and the heater!
Thankfully neither she or the camper were damaged!
Due to timings of holidays etc, Luna and Dana both completed part of their puppy training in the camper aged 9-10 weeks. The only downside was that we were a magnet for all small people at campsites who wanted to follow a pup
They both travelled as soon as we got them in the camper and have no travel issues, but sometimes I think that can be down to the luck of the dog.
Our advice, if you decide to go for a new addition to the family, is...
1. stock up on poo bags, when you think they've completed their poo and tie the bag closed, they always just have one wee extra poop
2. don't tie poo bag too quickly, see above
3. only buy clothes that have pockets to keep the poo bags in
4. have a spare lead, you always forget where you put the other one
5. a dog screw for the ground is a must
6. consider a hi-viz jacket, harness or collar for the dark walks back from the pub on the country road
7. consider asking your vet for Bravecto, it's a flea and tic prevention in tablet form, a bit expensive but lasts for 3 months - we holiday in west coast of Scotland regularly and have had no tics
8. be prepared to give your life over for the dog, they really are part of the family!
p.s. they don't poo that much!