That particular configuration gives an upobstructed passenger cabin, with the wing carry-though structure passing underneath the floor. Unless you want real rough-field capability, that or a low-wing design are the best approaches for a passenger aircraft. Would this be called a "Shackletonian" or just a "Shackleton Liner"? I keep in mind that Convair's "Liberator Liner" shared only wing and tail surfaces with the Liberator, and then it was the B-24N with the single vertical tail.
Further: I should note that the main landing gear length requirements are going to be the same with a mid- or low-wing in that you've got to keep the props clear of the ground at the highest gross weights and sink rates. A mid-wing like this actually lowers the passenger compartment relative to the ground for purposes of access and loading. Besides, a mid-wing does not need as much of a fairing into the fuselage as a low-wing would.