I am 5'11+ and I ride a 56 cm 26 inch LHT. It is ok off road just be very careful of roots, stones etc due to the low BB.I have rode singletrack with Schwalbe big apple 2.3's (it was a dry summer) without any problems. ree with Lee that you may want to consider the troll also. I have toured with my LHT and absolutely love the way the bike rides.
Here is a pic of my LHT riding offroad in the snow, it is running Nokian 2.2 studded tires with fenders.
P1020441 by DennisLitto, on Flickr