Thanks to all for the guidance. I passed on that F-150 w/ the 3.31 axle ratio. Then I found the perfect one (for me). Has Ecoboost, 3.73 locking, with Max Tow.
Low mileage 2014. Downside: It's in Florida waiting for a transporter and I'm in NW Washington. Could I have found one further from me?!
Isn't it amazing? Money and the internet make just about anything possible. The truck in this photo looks like mine but the side mirrors don't reflect the max tow package. It should be here in a couple of weeks. NOW the AS search begins. I may delay that search until after the prime summer camping season concludes and more units come up for sale on the used market.