I seem to recall from a previous thread..."Holiday Jets" possibly?...that Laker developed some unique take-off (reduced thrust) and climb techniques for its 1-11's that gave them just enough margin to make the 1-11 viable on these long legs. I'm sure the learned rog747 and others will fill the gaps
I am rather jealous of Mooncrest's Laker DC-10 recollection. My school ski-trips were always on Dan Air or Monarch 1-11's, save one glorious year where our ride both ways was on Monarch 720's