Extended warranties are they worth the cost

Don't know which brands you are looking at, but Forest River offers a second year of warranty coverage for $150 on their towables. I think you have to file and pay within 10 days of purchase or something. It covers the same stuff as the original one year warranty so it's definitely worth the $150. I don't know why they don't just ditch the minimal fee and just start including it.

Jayco is a standard two year warranty.

I wouldn't pay for any more coverage than that on a travel trailer.