Well, listen you are doing all the right things and your setup and husbandry sounds correct. Don't get discouraged and just space out the offerings a little more. Make sure to not handle him at all until he's eating for you. Definitely after a shed the animal will have a increased appetite. Most of my garter babies get their food left on a paper towel or small plate on the enclosure floor. Cali reds are very flighty and get spooked easily. Try feeding him by leaving the food on the floor in the tank. Remember to space the offerings and just be vigilant. Consider raising the hot spot to 88F on your thermostat. Your'e not failing, you just have to continue to tweak different things in the environment. We are here to help you get it right.