A 5.5' box with the gate down is more than enough to throw an outback in loaded without a bed extender. A couple of ratcheting straps and a flag, and you're good to go.

For more kayaks, it's hard to beat the TrackOne racks. Here's my setup with 3 kayaks at Convict Lake last month.

https://fishingfiend.smugmug.com/Tri...DSC_6111-L.jpg

that's just a great pic right there.