sorry, as far as i know, no such AE plugin exists. I don’t know why there’s no b-spline or bezier plugins, very strange, seems like there would be a huge market for it. Mocha kind of took over that part, I believe, for tracking, splines etc.
Anyways, for ease of use, I’d recommend mocha pro. I’m sure you’ve used mocha before and it will automatically track and remove(create a clean plate) for you. very easy to use. google youtube mocha pro rig removal for quick demos.
don’t forget a quick track in AE attached to a couple clone stamp tools to go around a curve can sometimes work farely well, too.(as long as the curve shape angle is unchanging)