I think Dometic and Engel sell portable freezers that will do what you want. They run off 12-24VDC or 120/230VAC. My larger one runs off a 100ahr battery for 4

I think Dometic and Engel sell portable freezers that will do what you want. They run off 12-24VDC or 120/230VAC. My larger one runs off a 100ahr battery for 4 days. You can set the temp from 20C to -4C. They are pricey though $500-900. You can get off brand ones that are cheaper.