Curious what lodge your son will be joining? In our lodge, if the weather got too bad, we would put the candidates in an open sided shelter. I really doubt your son will be allowed to create a "tent" like structure. Instead, we rolled up inside our 12 x 12 blue ground cloth. I have actually gone through the Ordeal many times and when it rain, I would just roll up in a cocoon. Because rope and stakes are not that much equipment, maybe you bring them and have him ask the people where he registers for the weekend if he can have the stakes and rope. If not, just take them home otherwise your son
