Official comment
There are a few options using the current release.
1) Manage your take off point so it's near the highest point. accepting you'll get increased overlap and reduced resolution in the lower sections (my preferred). You can manage this a little by adjusting your mission height to lower.
2) Take off from the lower area and ensure your mission height will clear the higher sections and increase the overlap to ensure your higher sections get sufficient overlap. This will give you increased resolution in the higher areas and planned resolution in the lower areas.
3) Fly the area in two or more missions ensuring they overlap, then process as a single job.