You know, I was thinking of this and thought why not ask? So, I posted the Qs in the Heartland Landmark forum and got this answer from Heartland.
Great question - we have several engineers at heartland and a director of engineering. LCI also has several engineers on staff and reviews our drawings as the come in for structural integrity. Landmark and Bighorn share the same engineer and we have an engineer for the Big Country and Elk Ridge line. These are the ones I know because I deal with these folks every day. I also know Sundance and Gateway have the same engineer. All of these folks are employees of Heartland and have offices in each plant. I'm sure the other brands are the same - I just have never been to their factories. I have included Andy from Lippert on this email chain who can tell you what they have for engineers in-house at LCI. Hope this helps