My answer is more of a philosophical response. Extended warranties and warranties you pay for are basically a form of insurance. Insurance has 2 purposes - 1) protect you against catastrophic loss should the insured events come to pass. 2) reduce the risk of future costs by betting you will have things go wrong. Complete loss of the fridge or AC in your RV is not a catastrophic event (devastates you financially) - the only possible exception I can see is that the RV is your full-time home, and you live in a climate and/or have a health condition that requires these appliances work.
If you self-insure, you would invest the cost of those extended warranties in accounts as a rainy-day fund for when things go wrong with those items. And probability says you will come out ahead, since the extended warranties are not offered at a loss (they are often more profitable than the sale of the item itself). The problem with self-insurance is that the risk is not spread across many units or people. There is a small but real chance that you could have costs that exceed the amount you set aside.
In my neck of the woods, the costs are about an hour's worth of repair labor with a couple of small parts. Obviously, the manufacturer does not expect to have claims on the majority of his extended warranties.
Other considerations in the decision would be the amount of the deductible and how much routine maintenance is expected (and must be documented) to support a claim. If the fridge and AC have to be serviced every year to maintain the warranty, then it is a really crummy deal. The other consideration is what the replacement cost with a new appliance (including installation labor) is. The latter is really the cap on your worst-case loss.
As you can tell, I'm not a big fan of paying for extended warranties. Others will have very different opinions.
just my thoughts and experiences, yours may differ