I purchased a warranty for an older trailer ('00) right before a cross-country road trip. Luckily I read the fine print before having any issues. I broke a leaf spring in NY, and did all the correct steps, and had no issues. Later my fridge went out, and they replaced the cooling unit.. My warranty already paid for itself.
One tip.. If at all possible, have your trailer repaired at the shop that sold you the warranty.. They take care of dealing with the warranty company themselves, and you don't have the back-and-forth. Also much less chance of being declined.. Just my experience.
Read the fine print.