Whether an extended warranty (more accurately an extended service plan) is a good fit for you depends on your willingness to buy the plan (they are pricey), do you have the financial resources and DIY aptitude to go it alone with most repairs when the warranty is gone? Keep in mind many components such the AC unit, fridge, furnace may have their own warranties past the trailer manufacturer's warranty. And, do yo feel lucky that nothing of a catastrophic nature will happen to your RV?
Now that I said all that, we bought a dealer offered 7 year plan on our 2013 WhiteHawk that is quite inclusive on what is covered. RV longevity (construction quality and components) give me the Willys, so I bought the warranty. Would most do what I did? Probably not, but my decision allows me to sleep well at night and develop insomnia over more important stuff in my life..........
Totally up to you and your own comfort zone.