A lot of people just say to put the money into the bank that you would have spent on it and be your own warranty company. It’s not bad advice as the warranty companies wouldn’t stay in business if they paid out more than they brought in. The gamble works for them.
That said, if you decide to do it, the Good Sam Extended Service Plan came highly recommended to me by a mobile RV tech and a service shop. Neither were selling it to me.
They approved repairs and paid out quickly when I had to use it.
I wouldn’t buy it until your 1 year warranty is nearly up, though.