Here’s an idea: why not just ignore the extremes, and to make a “fair and balanced” panel, put the Democrats in as the moderate conservatives and the socialists, greens AND libertarians in as the balancing agents?
It doesn’t have to be extreme socialists, libertarians and greens either; there’s plenty who lean those directions who are moderate, and that’s a message that’s been totally ignored in the US since the McCarthy era.
Let the viewers see what different but less extreme viewpoints look like.
But what do you dislike?