Freestanding woody design

I really want to build a woody at my apartment, but cannot drill into anything. I have ample backyard space to build a freestanding wall and was thinking of building a moonboard. Here are the plans for building a moonboard, which is sort of a cool idea by Ben Moon where his modular holds can be set into preset problems that are already graded for training purposes. Does anyone with more carpentry knowledge have any idea how I can support this?