My opinion would be that your friend now owns the wooden stand because it is a permanent structure. He does not own the portable stand, and the owner has a reasonable amout of time to retrieve it. After a certain amount of time is over, then your friend would then become the owner. I' m not a lawyer, just guessing, and I don' t know what the time frame would be.

I' d say hunt them both if you want. The owner of the portable stand does not have the right to hunt there anymore. He probably does have the right to retrieve his property.