I can and will. I would rather not cut up a winch line. If you are not picky about color, I have several samples of line that would be more than suitable for an extension that I can use. Won't hurt my feelings to cut one of those up.
I need some idea of what you are after. I do agree with the recommendations above and you'd get more utility out of a kinetic strap. Won't hurt a thing to use that as an extension. You can hurt a winch line by using it as a tow line though. They don't like shock load. A kinetic strap or even kinetic rope will do more than be an extension and can still be an extension. I will however, be more than glad to supply what you need if I can in the way of a winch line extension.