To update....
You can access the administrative endpoints (assuming you have admin privileges'), in a similar fashion to the linked post earlier. After you create an initial view, click on the "view" button by the views URL in its overview section. From that popup window, at the top right there is an "admin" link. Clicking on it allows you to find the "Update Layer Definition" REST endpoint.
The problem now, I've been playing around with the JSON and I'm unable to come up with a combination of existing JSON with the JSON in the linked solution, and have had no luck getting the layer definition to update.
