I'll 3rd the trailer idea. If I'm hauling more than one kayak I almost always use the trailer. When carrying on the roof, I use wing-style cradles. I don't like J-style cradles because the boats will catch a bunch of side wind that can twist the racks and cause failures. Just buy good stuff, not cheap Amazon-Chinese-Knock-Off-Junk. Thule, Yakima, Malone, Goodboy, Etc.

Mercy ceases to be a virtue when it enables further injustice. -Brent Weeks

~Molɔ̀ːn Labé Skýla~