Ive been running gravity feed for 200,000 miles on my '13, and 60,000 on my '17 (same tank, RDS 97 gallon tool/fuel box, I just moved it to the '17, which is a PITA due to bed height change and different spacing on the floor of the bed... and I had to move the drain location due to the narrowed width in the front of the bed...)
I leave it open all the time when I am hauling, but when I am DDing her, I shut it. Once or twice (or 6 or 7 times...) I saw more than a few drips of fuel under the truck near the fuel fill door, and it scared the chit out of me. Plus, on my '13, it leaked enough to short out my Airlift controller for my airbags...
Also, even though it says 97 gallon, I only fit 92 gallons in it the first time I filled it. AND.... once it drained, I can only fit 85-87 gallons in it... the drain is not on the bottom, so I cannot get all of the fuel out, and the filler neck extends 1-2 inches into the top of the tank, keeping me from filling it to its 97 gallon capacity... But, 85 "usable" gallons triples my capacity and range...