I just went through this exact sizing process. The LHT and Disc Trucker are kinda goofy, esp the 60 and 62. While the top tube lengths (ett) are different, longer on the 62, Surly relaxed the 62 seat tube angle compared to the 60. As a result, they have the same reach, both size frames will use the same size stem. I would go with the 62 for the longer head tube, but even this doesn't really matter, both frames have the same fork, the difference will be 20mm of spacers, fit is the same.

I'm 6-2, I wanted to use a Thudbuster, I bought a Soma Disc Saga instead (the size they call 60, which has a similar reach and 57.5cm seat tube). If the Disc Trucker had a sloping top tube I would have bought it.