Recreational vehicles are provided with a tapered duct connector and/or a conditioned air receiving sleeve that is positioned in an infra-ceiling space of the vehicle. The tapered duct connector comprises a connector inlet coupled to a conditioned air passage on a wall of the conditioned air receiving sleeve, and a connector outlet coupled to the supply duct, to fluidly couple the sleeve to the supply duct. The tapered duct connector comprises a transitional duct height that increases from the connector outlet to the connector inlet. The conditioned air passage of the conditioned air receiving sleeve, the tapered duct connector, and the supply duct is contained such that air can pass from the conditioned air opening of the conditioned air receiving sleeve, through the conditioned air receiving sleeve, and into the supply duct without contacting structural components in the infra-ceiling space of the recreational vehicle.