That all sounds very overpriced to me.
How many sets of tires can you get for the $1000+ they want for tire protection and sealing? Probably at least one and a half.
What electrical and mechanical failures are common on this trailer after the warranty period but before the first five years are up? I'd think $2200 would about cover replacing the fridge or any two of the other major appliances.
Gap coverage may be worthwhile, but it's also a lot of money.
I would save the money, perhaps squirrel some away in the bank for future repairs, and perhaps get a good roadside assistance program (AAA or Coach-Net or whatever your preference is and whatever has better coverage in your area). The rest of the money is better spent using your trailer. (If they're talking about adding this into a loan principal and financing the additional add-ons, make sure you add in whatever interest you pay on the additional principal as well when figuring how much it really costs.)