Thanks for your suggestion. We will continue to think about an option in the Extra Axis. For now, we created an improved template to interactively create the labels above the graph.
To plot 1/T on the x-axis, the value of 1/T is calculated using an Expression column in the data table. Then the issue seems to be how to display T above the graph.
To improve the current template, we made a file that will calculate the values for the T axis using variables to define the minimum, stride, and number of grid lines.
One example is given that calculates the locations of the grid based on an even stride.
A second example has an even grid.
Is this example similar to what you are looking for?