[cruisin]

Putting the boat on the top rack by itself does not have to involve lifting it straight up and sliding in place or the reverse to take it down. You simply install a set of rollers across the rear bar of the rack then set the front (top) of the boat on the rollers. Next, lift at the back with a buddy and slide/roll it onto the rack from the rear. The boat then rides top down and bow forward so it is more aerodynamic than any other configuration. To get it down, simply start sliding/rolling it back and lower the stern slowly to the ground then go up front and lift the bow off the rack and lower to the ground. Mission accomplished.

PS. this may even be possible single-handed if you are strong enough to lift one end of the boat by yourself.