I'm rebuilding an outbuilding to a Colorado mountain cabin. I want to make it into a bedroom with a bathroom. The structure is on concrete piers and there's no crawl space. I'll hire a plumber but I'm wondering if my design will work. The bathroom is on an outside wall. I'm going to build two 2x6 walls, one insulated and the other for plumbing. I want to put in a clawfoot bathtub, toilet, and sink. If I use a TOTO wall hung CT418FG with a Geberit 111.728 carrier sytem can I run the septic in the interior wall with the water? Can I vent the toilet out the end wall? Please see sketch.