Just don't blast the radio, keep them in a secure and cool area (I put my chin on the passenger seat buckled in and my car has a thermometer in it which is nice), don't aim the vents right at the carrier but maybe a bit above or something and pull over if you want to see if they will eat or drink.
I line my carrier with fleece and put a few sticks and some hay in there. I usually put a thin jacket over part of the carrier but it's always at risk for being nibbled, though the sun protection and place to hide I think is welcome. I try to drape it over the headrest and maneuver it so it doesn't touch the carrier that much. I don't think it's a huge deal, depends on the chin. Mine usually fusses and bites the bars for about 20 minutes, gradually calming down and then without fail she sleeps the rest of the way.