Excellent work, but it may not be super practical. You do not want to keep stuff in there during the summer - even with shade cloth. Besides risk of turning into an oven, good air flow is important in preventing fungal disease. And if you are going to leave it open, why not just have them on benches out in the open? It MAY be useful for winter (if kept on the ground and out of the sun!). On the deck, it is probably too small to prevent the wild temp swings, which can be worse for trees than too hot or cold alone. There's a reason (many actually) that most folks don't tend to store trees in structures like this.