I have traveled many a mile with a dog or two with me. You pretty much covered most things. I stop a little more than every two hours to let them out to do their thing. Keeping them warm in the cold is important as well as keeping them cool in the heat. I have always made provisions of sorts for when it rains so they will keep dry.
I haven't had much of a problem with motels either with the exception of Canada. Had problems with them in a few places.
I hope you have better luck with the Doggles than I. Mine just don't want to wear them and keep removing them.
It is a lot easier to travel with Sheba in my trike now than with the two wheels, but then I made a special place for her.