That's quite a lot! There are also clothes that strongly boost the heat dmg gained, like wool clothes or winter clothes in general. Putting them off might also help if you should have equipped any.
Most of the best heat reducing clothes can be found in chests across the world. Checking out the stores in town may give you some decent ones as well. Another accessory you can also buy in town are the Fire Reduction Charm Series. They also give heat resistance if I remember correctly. Depending on your reputation the town also starts selling more and powerful equipment.
If you have the dog form you can also use the scent trails to find your way swiftly through the desert. making it far enough in the desert will grant you a form that will greatly help with heat reduction.