[Montana Man]

One thing to consider is the vent location is determined, in part, by wall studs. They must be avoided at all costs.

This photo shows how our combo is mounted. This platform has a raised perimeter and a hole for the drain line. The inside dimensions of the raised portion is the outside dimensions of the combo's feet, thus captivating the unit and prevents movement. The platform is waterproofed just in case of leaks. Just an idea since the optional drain pan seems inefficient to me.