We people that have had their refrigerators worked on in a class A. One had the compressor replaced and they used the outside small access port to get to it. They also moved it out from the rear a few inches. I don't know of any that failed during warranty though so can't tell you what Kitchen Aid will say.
We had a MH with a residential fridge and a non pure sine inverter. The fridge and microwave didn't like that so we swapped for a pure sine inverter before anything died.
I believe you are correct on the extended warranty.
