Your problem is ...
No fans. ... Get a small oscilliating fan ..... No, get 2!
Vent that hood outside.. ... Your plant is drooping due to the high humidity and heat. .... Do you sometimes feel moisture on the inside of the tent?
edit:
I see your vent system, my bad... All the same, an oscillating fan is a must.
And if that heat is not being expelled outdoors and is just being recycled it won't help much.