My mid-30's pickup seat mounts to a perimeter sheet metal "skirt" that finishes off the seat mounting nicely. This mounting scheme also creates a reasonable volume between the floor and the underside of the bench seat so I'm considering mounting my heater / AC unit in that area which would free-up the already small behind-dash area, as well as the firewall (hoses would route under the cab instead of going through the firewall).

I know under-seat heaters have been around for a long time. Anyone ever seen the A/C unit included?