Several years ago, I did it. Drove across country, dogs in the 29ft Keystone trailer, during the winter with the propane furnace running (both for them and to keep water from freezing). I installed a wifi camera and kept a VERY close eye on them early on. They made it just fine. Never mind the details, I had to do it that way. Since then, I've read that so many here don't like the idea so I'm probably not going to do it again. Well, now in a motorhome so it's irrelevant for me. The point is, if you must do it for some reason, try the wifi camera and don't actually decide to do it until you're satisfied. Obviously, not all dogs are the same. Mine were fine.
To those who think I was a bad Daddy, well... the alternative would have been giving them up to the pound or something similar. I simply had to find a way to be satisfied and the camera did the trick. Also, to someone contemplating this in the future... remember I said my trip was in the winter. My approach would not have been even considered in warmer temperatures.