Following the principle that the easier it is to deploy, the more use it will get (and the less damage to either boat or body), we initially tried loading our 65 lb. polyurethane kayak on the sport rack and realized far too much effort was required. Instead we purchased a “new technology” (drop stitch) inflatable Sea Eagle Razorlite kayak. Measures 12’10” long and 28” wide, and exactly half the weight at just 33 lb. Dimensions fit very easily on either side on the sport racks. I load from the bow, upside down. Best part is I easily do this as a one-person loading operation. So easy, we deploy daily upon dropping anchor, partly to allow full sun exposure to the solar panel.
One modification we made is installing two vertical stainless steel posts which act as a second set of hands as I slide the kayak from bow toward stern. I have replicated this on both port and starboard, and stow a similar “drop stitch” inflatable Tower SUP board on the starboard side. The SUP board weighs all of 25 lb., so light I can even lift up using just one hand!
If you are thinking “inflatable” means cheap or inferior performance, familiarize yourself with drop stitch technology, which allows inflation to over 10 psi. This is not a child’s pool toy! At 10 psi these boats inflate almost hard as a rock, very rigid, and paddle great! And they get USED A LOT because they are both easy to deploy and a joy to paddle. Stability? We bring our 70 lb. Golden Retriever along in / on either one!