I need straight paths with end markers for associating text to parts of the image. For better readability, it needs to be high-contrast, i.e. a white line with black outline.

Stroke to path will create a group of a box and a circle from the line with end marker. This makes placement of the markers more difficult, as with the node tool it is just a matter of dragging the end nodes of a line segment.

I will try to place the markers as line for now and only finally converting them to an outline.