Yes, we use relaxed UVs on the L1011, we found this method to be more optimal for specific sections of this aircraft. It didn't make much of a difference for us, since our in-house liveries are painted using 3D decals which is the best standard for quality, but I understand the traditional Photoshop painting method would be quite tricky with such UV layouts.
There is an .fbx model included for you to project your graphical elements onto the relaxed UVs using the likes of Substance Painter. This is the best and quickest solution.
Max's post in Paintkit was marked as the answer