Bought a Nucanoe 10 foot last year. Wanted the 12 foot, but after doing some measuring decided I could fit the 10 on the truck top with plenty of room to turn the 5er. I have a GMC 2500 with 6 1/2 foot bed.
I only did one short camping trip to a close by lake last fall but I had plenty of room for tight turns backing into and pulling out of the campsite. One maybe unexpected plus. I may have gotten a little better fuel mileage. The kayak flipped upside down on roof seemed to break the wind hitting the front of the 5er a little and that may have helped some. I am taking a longer trip next month where I will do a real world test of the mileage. Be nice if it really did help a little.