What I think Halueja means is at 5:35
I personally would much rather have this than some outdoor thing with a tree. It just looks so lackluster to me. Having a very tall ceiling with metal support beams that you could cling onto and stuff would be so much more fun.
I reckon people will play this mod mostly in SP so having the whole setup in between the two trampolines is unceccessary.
Or you could do what Obazu said this morning and make something like this: