We occasionally leave the dogs in the trailer for short periods of time - an hour or two with no issues. Have only done it with hookups though so the AC is on.
If you haven't done this before though, I would recommend you see how they react when you leave. Go just far enough away that you can hear them if they start to make a racket. It might take the dogs some time to get used to being left alone.
We were camped one time next a family that took off in the morning and left their 2 dogs in the trailer for most of the day. They barked almost the whole time. Seemed like as soon as they settled down someone would drive past, or kids would ride their bikes past the trailer and the barking would start all over again.