Our apologies for the delay getting you a response. In order to achieve the shot that you are describing we would recommend using either a KC-8 or a KC-12 with a Rev2 Pan/Tilt Head mounted to the end of it.
By putting the tripod at or just below the crest of the due you would be able to have the crane arm low to the ground pointed at your actors as they climb the dune, swing the arm behind them and rotate the Rev2 head to follow them as they pass the crane's tripod and then boom up to get the reveal shot.
This unfortunately would require hiking with some of our larger equipment, but that is not an impossible thing to do, thankfully our cranes brake down to smaller sections that make them easier to hike with and transport. For example, here is a blog post where some of our sponsored shooters used their crane throughout Nepal, sometimes in locations that they could only get to by hiking.
Hope this helps, good luck with the shoot!