How to set up customized parameter?

How to set up customized parameter?

Hi, I am working with Image Processor.
It is very nice that you have the "Roughness" parameter for features, which is the convex hull area/feature area
But I wonder if it is possible to get convex hull perimeter also as a customized parameter, which can not be found in the list of all parameters. I know I can use the "ClearUp-Replace with convex hull" to get the data, but it means another layer, extra steps and more time for large batches of images; And I have to calculate in the excel by myself, which is time-consuming
 Since you already have the "Roughness" parameter for the formula of customized parameter, is it possible to use the convex hull perimeter directly in the formula without replacing with another convex hull layer?
Thanks in advance for your help!