My 2018 F150 4x4 SuperCrew came with the optional 36 gallon tank and I love it. I have the 3.5L Eco-Boost V6 Kevin used, and my milage per tank runs somewhere between 500-700miles - usually around 600+. depending on my speed, prevailing winds, how fast I'm travelling etc. I love having that kind of range; I can use GasBuddy to help me shop for cheaper gasoline along my route as I travel. I don't usually drain the tank dry until I'm running on the sand in the bottom of the tank, but usually begin to think about refueling at 3/8ths or less tank remaining - that is why I reported ranges less than 700+, even though at 60mph I am certain I can average 20mpg unless I am climbing up and gaining elevation. I typically get around 18-19mpg locally at 550 feet above sea level at 70-75mph on the highway, which is very similar to my 2015 4Runner, but my F-150 accelerates faster.
Kevin - as to drawer system I have been looking at Decked.com very seriously - they offer a pair of roll out drawer for the 5.5 foot bed starting at $1249.99. I already have added an ARE bed cap ( https://www.4are.com/product/z/ ) - looks fine and keeps the rain out - don't know about desert dust yet. Not cheap though.
I am still on the fence about bigger tires - I didn't lift my 4Runner and it has taken me some amazing places with the stock suspension and good AT tires - I ran Cooper AT3s for 40,000 miles with good success.