[Montana Man]

First, good job on the photos with drawings. Personally, I would mount the unit on the bottom. Mine had a base to set a unit on but even then it needed reinforcement. If your plumbing connections are above the washer then lucky you. You will have access to the valves. I wouldn't trust the "cut here" sticker, a stud finder is your friend. Then, vent straight out or slightly lower than the outlet on the unit. After installation, I would build a removable shelf above the unit and call it done. Let us know how it ends.