I have taken the implementation mentioned above (injecting JavaScript) and that works for me. All I do is simply set the visibility of the webview to be hidden under other UI elements. I was also thinking of doing the same with selenium. I have used selenium with Chrome in Python and it's great but like you mentioned it is not easy to not show the browser window. But I think it might be possible to just not show the component in Android. I'll have to try.
