One issue to consider is that there has been poor availability in many sizes for the Surly LHT. Check and see if you'll get the size you need in the timeframe you have.
I wouldn't sweat the 26/700 issue. If you need the lower stand over 26" makes sense and you'll get any tires you would like to run in that size. Also the LHTs seem to be sized quite large so double check that the size you select will work. Most people are going one size down from what they would ride in a road frame.