I think I'm going to go with just one of those trunk kits. I really don't want to be carrying that rack or a hitch all the time with the extra weight and aero drawbacks.
For those who are interested, I was seriously looking at getting a Westin kit which seems to have a single screw mount tower for trucks, either for racks or for their through-hole systems (for camper tops, or permanent rooftop installations). For reference, the MS3's holes are M6X1.0 thread, approximately 103.5mm side to side and 67.7mm front to back.