yeah, little hard if you dont have permanent racks as most of the soft racks are meant for surfboards
i've got a mate who has a 12 foot laird and he uses these
www.anacondastores.com/water/kayaksi personally use a set of these, they dont come with tie downs like the other ones, you just use your own
www.jervisbaykayaks.com.au/roofrack-systems/watersports-racks/solution-traveller-soft-racksi find both of these racks good as they have different widths so they are good for sups, but also good for surfboards, racing mals, whatever you want to put on them
i would probably use these on the highway as long as it was multi lane, i've had em on a single lane road doing just shy of 100 and you get alot of bounce when something comes the other way that is a little bigger than you, probably fine on the highway as everyone is going the same way
Jarryd