Most parks have a rule against leaving dogs outside unattended, even if tied.
We have always left our dogs in the RV with air running if hot when sightseeing. But they have always been very quiet and calm Goldens. We would take them for a walk first and they retire to a dark corner for a nice nap. And still asleep when we return. But we have also had neighbors whose dogs would bark continuously the entire time they were gone. Do they bark at people or sudden noises? If unsure, close all shades so they can’t see and bark at people or dogs passing by. And hang around outside for a while after leaving them to see if they start barking.