What's the best kind of dog for traveling(see details)?

In 3 months time, I will be purchasing a Westfalia camper van, and a puppy, and hitting the road!

I am allergic to most dogs, but I do OK around poodles and the like as long as they are regularly bathed. It is my intention to get some kind of poodle or Portuguese water dog (also good for allergy sufferers) mix.

I understand that both these dogs are high energy and need daily, if not constant mental and physical exercise. While I do intend to walk and/or run my dog multiple times a day while on my journey as well as mental training and tricks, I am worried that hours on the road could cause the dog to get bored, and could lead to behavior problems.

What would be the best mix to get, bearing in mind the allergies, road trip hours, and size? (I’d like something that’s about knee high at the shoulder as an adult.) Also are there any activities I could give my puppy while I’m driving and can’t play with it?