Here is this mornings idea for anchoring the Yurt walls to the ground, internally, without any ropes to trip people in the dark palya night. Staking them to the ground makes sense. However, I worry that trying to pound a stake into the ground will end up damaging the foam wall with a misplaced hammer blow. So I am going to try and use long, large diameter lag type screws, driven with a cordless drill into the playa.