Since fences are categorized as landscape elements, they are automatically attached to the terrain and cannot be elevated.
To represent a gravel board, you can use a wall element.
Then you can import a custom fence and arched trellis from an online catalog like SketchUp 3D Warehouse.
Visit the SketchUp 3D Warehouse to download the custom elements you need.
Import the components into your Envisioneer model by going to file>import>object wizard>select>skp file type
Once imported, group the individual elements together (e.g., panels, posts, gravel boards).
The grouped object can then be freely elevated and positioned as needed.