The questions you are asking are good ones and point to a fundamental difference between UK dogs and ours. UK handlers get their dogs out in the morning, often before a trial and take off the rough edges. In North America, we are usually on the road for five or six hours the day before, with nowhere to school on the day of. It makes demands of the temperaments on our dogs, not particularly tested on dogs from the UK, where an hour is a long commute to a trial.
My own dogs have suffered on extended road trips where mostly they just do not get to hang around and behave like dogs. It is stressful in the long haul, being on the road for more than a month, and sometimes two.
If you plan to be a serious roadie, make sure your dog does not spend the entire day hanging around, being a dog. Get him accustomed to crate time and down time. They should accept confinement as part of a normal train of events. Take him on short trips in the car, so they see automobile rides as no big deal. Take the very young with you on road trips so that they too get the hang of it and see it as normal.
At the trials, take the dogs for a long walk. It will help them relax and take their trip in stride.
Cultivate friends, on your routes that don't mind if you stop and exercise the dogs or put them around some sheep briefly. Play that cool. Never abuse such a privilege, or pay down the road. Don't have your dogs pissing or pooping anywhere near their houses or gardens, creating pissing matches between and the home dogs.