Planar Slice tool doesn't work with Reality mesh. To extract profiles from mesh planar slice is very useful. Either improve planar slice tool or add similar tool working with reality mesh. Project line or stencil doesn't give expected results as need to extract underlying geometry more accurately.
We need something that can reliably create either a mesh that follows the terrain/surface like the stencil tool is supposed to do or one that can slice an existing mesh using a 2D shapes draped onto it.
We need to create a mesh with thickness to represent garden bed areas soil depths in large quantities in one step. A tool that does it one at a time is not practical.