There were quite a few topics that were asking for ways to change/manipulate the way the TTV Message Boards look to better fit their preferences. Be it to change the boards back to their original appearance, or to make a new skin altogether.
Unfortunately I searched high and low for a solution to this issue, because it's something I felt would be a good feature to include, and turned up no results. The developers of the Message Board software have expressed no interests in user-wide customization, and any potential for this feature would have to be developed ourselves.
So instead I found a work around for you guys to try that should do everything you want.
You can use a browser extension called "Stylish" to download some pre-made themes I made for you guys. With this extension you can switch back between the new board look, the classic boards, or anything you can imagine with the click of a button.
Link to premade themes: https://userstyles.org/styles/browse/ttvpodcast
Keep in mind that you, the community, can develop your own themes and upload them here too so that there's an expanded gallery of themes to choose from (provided you know a little CSS)
Hope this is helpful, have fun!