Sarah that is an interesting creation.
I would not worry about it getting too hot in summer, since there is sun only 50% of the area, you have a door and roof vents.
My greenhouse reaches 40-45C and plants are fine.Light is more vital and I don’t recommend shading.
Not sure why you think it will be high humidity, I would grow anything that likes warmth, usual suspects from aubergines and melons to sweet potatoes and Malabar spinach. So much you can try.
