How can I preview a project with the mobile skin without having to publish it? I.e. using the preview button and not an actual mobile phone.
In VT PRO click on "Preview" and when you see the tour come up, press Ctrl + N. This'll open the tour in Chrome (if this is your default browser). Press F12 and a click on the mobile/tablet icon on the left of the console, you'll be able to choose what mobile you want to emulate. Once you did that, just click F5 then so the tour refreshes for mobile.
That's it, you'll see on your computer what the tour would look like on that mobile.