it’s about 96″. following friz’s lead, I positioned the TD so that the front edge (the outside edge, the corner where panel 2 meets panels 3 and 4) at the front corner of the frame. I then cut the rear of the frame so the end is under the rear corners of the TD. that positioning resulted in a tongue weight (unloaded) of about 50lb, or roughly 10% of the total weight. I have since built a tongue box which has increased the tongue weight a bit, with no adverse effects on trailering. the location of the battery as recommended by CLC is right over the axle so that doesn’t affect tongue weight. some folks have mounted the battery under the camper, but that is another discussion.
ken