Wave enough $$$$ under the dealership's nose and they may make exactly what you want magically become available. Remember the Mercury Marauder? Supposedly it was never available in red but I know a wealthy old woman who got what is most likely the only red Marauder ever made. Wouldn't say how much extra that cost her. Would have required either sending the body and other parts down a line currently spraying that color, or stopping whatever color was currently on the Marauder line, flushing everything, shooting the red, then flushing that to return to one of the standard colors. Mercedes did the same a couple years ago for spraying red onto one of their models that was only available in black, silver or white.
Just ask the dealer "How much will it cost me to get the second row bench instead of captain's chairs along with the rest of the fancy luxury package?" A good dealer will make things happen to make a sale. An old friend of the family bought a 1967 Chevy Caprice with 396, Muncie 4 speed with floor shift and bench front seat. A combination that "wasn't available" but he got it anyway by throwing enough money at the dealer.
I'd expect having the seat supplier put leather on a 2nd row bench would be *significantly cheaper* than having an unavailable color sprayed onto the truck.
BTW, what use is the sliding middle part of the bench? Run it forward and its bottom nearly touches the back of the front console. If you need more space just fold it down.
That could be a solution, buy the truck with the rear captains seats then buy a used middle seat and contact one of those places that does aftermarket leather replacement upholstery. "I just need the middle part, not the entire 2nd row." Take it all to an upholstery shop, find one that will also install the midlle seat.