As long as you have good tires, I would not worry about it. We used to make annual trips from DFW area to Colorado every July towing our 35' 5er behind our F350, traveling from about 7-8 am, reaching Texas panhandle mid afternoon, and usually stopping in stopping somewhere in New Mexico late in the day. Around 10 hours or more depending on where we stopped. Mid day temps across north TX and the TX panhandle were usually 100+ and as high as 106. Truck temperature never went above the normal temp range. Even stopped on a remote section of I-40 for 45 minutes one time due to highway closed for an accident. Michelin tires on both the truck and 5er and tire temps were never overly high as shown on both my TPMS and an infrared thermometer. Relax and enjoy the trip.