Thanks for the replies people! Yes only 10 miles of gravel over 300 miles total isn't a big deal. I don't even need to ride any gravel but it helps with the route. Anyway I've noticed that a good number of long haulers prefer a wider tire, and now many claim the larger tire to be as efficient in long endurance rides so that's why I was asking what size (32mm to 40mm) would work best.
I'm a little disappointed in the less then stellar comments on gravel kings. I'm inclined to think I don't need the extra flat protection that the GK +, Gatorskin, ReFuse have. I've ridden these routes and area on 25mm Four Seasons and GP4KsII tubed with maybe a puncture every 20 days. Obviously a rough estimate but we don't have goat heads or anything. When I went tubeless I've yet to have a puncture that won't seal.
I think I will try the Maxxis Velocita EXO. As I noted before I like the sidewall protection, dual compound and the high wear center tread.