We show our dogs so we are always traveling with three Golden Retrievers. We use Xpens and tie out lines if we are sitting outside with them.
As to food, we carry a full size 40lb bag in our Van, I have a feeding station inside the trailer and a cupboard that is devoted to their gear, food, canned salmon, dog first aid kit, and grooming equipment.
Traveling with large dogs is very workable if you just pay attention and make sure they don't bother anyone. We have been traveling with our dogs for many years and have never had a complaint.