He's actually very mild mannered and I don't think you can argue that he's that much of a nutcase if he worked with Obama on some issues. This is something Obama has no problem admitting to either.
He's a "straight talker" which means he has a record of saying outrageous things that wear very badly. Think of what people claimed made Joe Biden unelectable, and then shackle them to what everyone would agree is a set of policy positions at one extreme of our spectrum. It's hard to get elected if you can get characterized as not a serious candidate.
Even if they are "extreme" by "our" standards, I don't see those positions resulting in losses in KY, WV, AR, GA, SC and the Dakotas.
This guy would motivate religious southerns/Evangelicals around the country more so than Bush did. To have him starting off with only 100 or so electoral votes is more fantasy than reality.
That being said, yes, I think he'd lose pretty badly unless Obama was sitting on Bush type approval ratings.