The Thule is a good way to go.
I have used it with my 16' Adventure and it spanned the kayak nicely.
The crossbars are spaced 5' 9" on center in this pic.
The crossbars can be lifted out of their bases in just a few seconds, no need to remove the base mounts.
Its a very versatile rig, the Model #421 shown here fits all 3 of my trucks. Chevy Dually, and both Frontier Models.