I installed a Haier 9.8 in my coach about 3 years ago and the compressor failed in 7 months running on a pure sine wave inverter. The factory said there is no warranty when installed in a motorhome. I put the Dometic back in and later sold the motorhome. My current coach had a Dometic side by side and was 32 inches wide. I installed a Insignia brand 10 cu ft with freezer on the bottom and built a slide out pantry using the rest of the width. I run a pure sine wave Xantrex 3000 watt inverter.
You could run a 400 watt pure sine wave inverter and wire it directly to the fridge so thats the only thing running off of it.