Nobody will like my advice on this and I'll probably get flamed on this, but here goes anyway:
Our solution to this issue is simple: We don't bring the four-legged pets with us when camping, ever.
They either stay at a friends, get boarded, or stay at the house and we hire a pet-sitter to come by every so often to check on and play with them (usually the latter). We find this is much, MUCH easier and less stressful on all involved.
Bringing them along just causes way too many difficulties that we do not want to deal with (most of which have already been mentioned in this thread).
I know I'm in the minority, and I know a lot of RV owners get an RV specifically so they can take their pets with them. That is not us, though. I like the freedom of not having to worry about the pets when we travel.
Will