Thricomes develop when the buds are mostly done growing, that been in the last 2 weeks, so patience. I would be careful with those feedings, 2.6 EC / 1300 PPM is too high in my opinion, If your ambient temperatures outside the tent are close to 40°C as you say then short of using an air conditioner, there's nothing you can do. What I do on summer time is flower regular or feminized strains on 12/12 with the lights on during the night, when it is cooler.