I have an existing WP site using a child theme of WP TwentyFourteen. The site runs on hardware owned by my company in a colocation facility and I have root access to it.
I want to be able to re-theme the site in the background (which may take a few hours).
Every time I want to edit the Fixer child theme, it insists on being activated, which then trashes my live site.
I did a support chat (don't recall with who). Support person first recommended creating a whole new private site by copying the current site. While I can do that, I think that will take a bunch of hours.
Support person then recommended Develop Themes Behind the Scenes , which has links to a bunch of theme switcher plugins, some of which are still current. I also did some searching for this type of plugin.
I will be doing new menus and some new pages for the new theme anyway, so it looks likely that I can work without changing the settings and pages that the current live theme is using.
So far I have tried:
* 'theme per user' - does not support child themes, which is why I want the plugin.
* 'theme test drive' - turning on upfront still trashed the live site
* 'WP theme test' - seems to work except bbPress Forums List quick code does not work at all and bbPress Topics lose all formatting on the topic text and do not display any comments at all, so I can't use this one either
* 'Advanced theme switcher' - turning on upfront still trashed the live site
Is there a theme switcher/previewer plugin that works with the Upfront theme builder? By 'works' I mean it leaves undisturbed a non-Upfront theme while configuring a new Upfront-based theme in the background.