Hey Troy, just noticed you are in Carthage. I've got something that might work that you're more than welcomed to use for your trip if it fits. A good friend in Carthage made it for me for a trip we took to Falcon a few years ago... in his GMC Sierra pulling his boat.
I was impressed with his quick effort (oil field guy) as he had never seen a kayak rack until he made it. Its semi adjustable as he had all the pipe threaded. I am planning to be in Carthage in the next day or two (flexible) if you want to check it out. It will definitely carry the weight of four kayaks. All you would need are 4 threaded extension pipes of about 36 inches each to make it work. Just pm me if interested. If anyone else up this way needs use it sometime, just let me know.
This is one of the corners that would need extensions screwed in.