Well I drive a Ford Ranger & use tie down straps like the ones used to strap dirt bikes. I run them through the scupper holes with the tail gate down & tighten down. I use my red pdf to clip on the end of the kayak & it's not going ANYWHERE! I can stack a second kayak on top but it's not as secure as just with one. It sticks out but no need to get an additonal rack or extender when you don't really need one. Like I said if it's just my Fish N Dive on there when it's tight. It's tight. I take it on the freeway ect with no worries.
