This trip is meant to be played without GPS. I would recommend using LittleNavMap with google maps satellite layer. - https://www.avsim.com/forums/topic/548994-new-maps-for-lnm/
Just set “show aircraft position” and “show aircraft trail” to off.

The terrain is quite diverse and has so many features and color so  it's really easy to get disoriented. Be prepared for some  backtracking and have some places to return to if you get lost.

First flight plan: https://flightsim.to/file/41817/namib-desert-navigation-challenge-1

If you crave more STOL landing challenges check my Idaho flight plans