RV people and pets seem to go hand in hand on this forum.
I really don't recommend taking a dog along if your intent is to spend significant time in our national parks for there are very strict rules with dogs. National Forests, Bureau Of Land Management, and Wilderness camp grounds are much more relaxed which is where we'll sometimes get an ear full of such noise pollution. I can't comment with private camp grounds for we avoid them.
I occasionally will see a cat resting on a dash board with owners away which never bother anyone including nature.
Regarding leaving pets on a hot day, a heavily shaded rig with a power roof vent running seems to do it right. Blazing sun and a/c dependency, I am not sure about that. As for cold days requiring heat, I see no harm in setting the furnace down so it isn't running all the time, and provide some snuggles for your cat or dog.
I would think it is best to take your dogs hiking with you, but stay off national park trails for you'll get into big trouble.
Keep in-mind that my comments are from a non-pet owner so I don't have personal experience vacationing with a pet. Just sharing my observations.
