Yes, you can edit the extension itself to customize it for your use.
I’d honestly suggest just messing with the parameters there, and try it over and over again until it does what you want. Each time you edit the code and save the file, you can just select Extensions>Previous Extension (and then undo) to try out its function. You don’t need to restart Inkscape in order for the changes to take effect, and the worst thing that can go wrong would be that you get an error message. Remember that as a python file, it is sensitive to invisible whitespaces.
I think that adjusting the scale parameters should be straightforward. I don’t know exactly how all the bend parameters work. One other thing you can do is save an SVG file with a single shape and a bend preset that you like. If you open that file with a text editor, you can see what parameters look good to you.
