It sounds like a great idea to have a large cage mounted against the wall but it does have some contradictions.
First of all is that humidity from the enclosure (whether a rainforest environment, or just urine, spilt water, feces ect.) will ruin materials that make the cage and the wall. The enclosure should be self contained(4 sides plus top and bottom) and then mounted onto the wall. A water proof and heat resistant material should be used. Pine should be okay if properly sealed however I"m no carpenter. All my customs begin with 2x4's and plywood. I recently tried a rubber-based deck covering to line a tortoise table. A new adventure, it so far looks like it is thoroughly water resistant, easy to clean, and plenty durable enough to withstand digging attempts.
In comparison, I have some melamine enclosures that worked really well for a while, but a combination of heat and humidity cracked the surface layer and after that the wood quickly deteriorated.