The Coleman Legacy is not a "ultra-lite trailer line". It falls in the GVWR range of 7000 pounds to 9000 pounds. That's a "heavy trailer"... There are light weight models in some other Coleman lines, but the Legacy is a "half ton tow vehicle or larger" type trailer line. Are you considering the Coleman and Coleman Light lines? They are much smaller and lighter than the Legacy line. From the information on the Keystone website, the lightest Legacy floorplan has a tongue weight of 605 pounds (empty weight). Typically most receivers on today's tow vehicles have a "maximum tongue weight rating" of 500 pounds without a weight distribution hitch and around 1000-1200 pounds with a W/D hitch. So, the Legacy line will nearly always require a W/D hitch.
As George posted, different models of the Coleman Legacy line have different total weights, different tongue weights and some could be managed by larger vehicles without a weight distribution hitch. On the other hand, even the smallest would require a W/D hitch on some "barely adequate tow vehicles"...
Then there is the caution/warning about not using a weight distribution hitch on some "uni-body vehicles". So, there's much more information required to the question: "Do I need a weight distribution hitch to tow a Coleman Legacy trailer"... So, to give you any "reliable information" members would need to know which Legacy model, what tow vehicle you'll be using, how you'll load the trailer and how many people/how much cargo will be in the tow vehicle as well as "where you'll be towing the trailer"... All those play a key role in how you'll need to set up the rig.