My husband and I also have a travel trailer, and we take both of our Yorkies along. They are very good, when they are inside the travel trailer, sitting at the door, watching people.
But when we are sitting outside, and people pass by, if my girls bark, I tap an empty paper towel roll on my chair and say, "Quiet!" in a firm, voice.
The younger ones will learn from the older ones. So, if you can teach the older ones "Quiet", the younger ones will learn, as well.
I would never want my girls to be a nuisance to to other campers.
Good luck and enjoy the camping season!
Sheila |