mini fridge in the truck

Hey guys I'm about to finish up with my trainer and hope to soon be getting my own truck. In the past my biggest expense otr was eating I planning to cut that way down this time by cooking in the truck. I want to get a small refrigerator and I mean an actual refrigerator not a plug in cooler, I'm planning in keeping chicken breast and maybe a couple of skirt steaks in there and I just don't trust the coolers to keep things cold enough. So I'm wondering if anyone else here has a mini fridge in their truck if so can the apu keep it running constantly? Also how big should I go? Think they measure them in cubic feet? and are those things cold enough to keep meat from going bad? Can the small freezers in them actually keep frozen meat frozen? Thanks in advance for the help.