Who tries livePreview for nsPage, finds that it's no so much comfortable, since size/position of its output doesn't allow a useful comparison with front image or with wikicode. VisualEditor could be a good solution, but presently it have limitations dealing with wikisource nsPage, mostly when adding fastly complex format, without the help of our beloved tools.
Far from being a professional script, it is just to proof that it can be done.
If there's any better solution for that issue, please tell me!
Alex brollo (from it.source)