I speak from experience that the extended warranties are not worth it. We bought one with our new camper 5 years ago and when we had a problem with the heater we called to have it repaired. They took out the heater and found a broken wire. They called it an adjustment.
This is how they get away with not covering things. When you read the book you get you will see 3 pages of stuff they cover and 8 pages of stuff they do not. This is just like a tire warranty. They will not cover a flat tire unless you can prove it was the tire and not something in the road. I would be more inclined to trust the 2nd year manufacturers warranty.