I got a Sharp Carousel Stainless steel. I think it was $80 at Home Depot. I could look but it like the smallest microwave they make 0.7 cubic feet. That's the standard size smallest microwave they sell in big box stores. It was only like $15 more for stainless steel model
There’s no specific microwave. Take a look at wattage of it - should be less then truck’s inverter. And don’t by a microwave with button to open it - it will shake and make noise at each bump.