Hooks and ropes
We need to hook the tea house to the ground using tensionning system that can induce a lot of tension. And we need to figure out a way of planting it into the ground, only on 20cm, and to keep everything in check.
The idea is to multiply the threads in the corner of the plastic sheets (there's one hole every 50cm in them, so using three of them should be ok). It will help spreading the load. We can then use some big hooks. The kind which might require a drill to stay in the ground.