Extended warranties have been thoroughly discussed here and on other forums. There will always be someone telling how they saved big money with one, but they seem to be the rare exception. Keep in mind that the dealer keeps about half of the cost for commissions, and the exclusions can really bite you in the you know where.
On top of being pricey and the exclusions, repairs will have to be done by an approved vendor, which may cause delays and frustration. One more layer of approval to clear before getting your repairs.
I purchased one on my fifth wheel and never had a claim. Skipped it on my next two rigs and still haven't had a claimable repair in several years and many miles. I am way ahead moneywise to have a dedicated RV repair fund.
Bad decisions make great stories!