I shoot my tires every time I stop. At least 300 times by now. What I look for is a difference of temperature between them.
Many things play a part on tire temperature including sun, wind, exhaust and, of course, the tire pressure itself.
A tire that runs hotter than the others by 10 to 15 degrees will get my attention and I'll monitor that tire every day in the morning before hitting the road.
You will develop a feel for the temps after several trips. It's good exercise and gives you a chance to do a visual of your RV during the walk around.