I see a lot of people using air mattresses for car camping in the summer. In less than optimal summer temperature, an air mattress will conduct heat away from your body and to the surrounding air. If you or someone in your family wants an air mattress then put a groundsheet ON TOP of the air mattress to insulate yourself from the cold air mattress.


No matter the quality of your sleeping bag, the weight of your body will compress the part under you. This is why a ground sheet is so important for a good nights sleep.


For a pillow I just stuff the sleeping bag's stuff sack, a T-shirt or something similar full of whatever fluffy clothes or other items that happen to be nearby.


Take notice of where the sun will rise to roast you in your tent. If you can't position your tent so it is in the shade in the earliest morning hours then consider a tarp or something similar to give some minimum cover.