If you want it that close reversing it like that is needed. If you want to know the kerf on a single piece of material today. Cut a small bit and measure it then set kerf and cut your design.
If you want to set a kerf on the fly in Inkscape you can set your cut line to the desired kerf size, then in Fill and Stroke (Shft+Ctrl_F) set the stroke style to that number and under Path pick Stroke to Path (Ctrl+Alt+C) and you will have two lines and Break Apart in the same dropdown will make them separate objects.
Then deleting the inner one will leave the cut to be exactly on the original line. 