Details to the layout itself see in Layout & Legend
If you prefer to see the wide layout in Basecamp too, you only need to change the so called TYP file for the map. The easiest way to do this is by using JaVaWa GMTK.
Unzip the content to any directory. Remember your directory, we will need the 2020p.typ and the 2020pn.typ
Download & Install JaVaWa GMTK
How to finally handle the change of the TYP file with JaVaWa, have a look at the little video where I change from Thin to Wide layout: