Bob, the questions you have to ask are - how much extra food do you need, and how often is this likely to be a need.
I have had both Engel and National Luna fridges. Both were combo units that had freezer/fridge, freezer/freezer, or fridge/fridge capabilities. If you have the coin, the National Luna comes in stainless steel. But honestly, the Engel and the NL were both fantastic units.
We also have a Yeti 45 cooler. (a worthwhile investment).
If this is a need that you will face on a regular basis, I'd look at a small 35 or 45 quart fridge/freezer and keep it in your tow vehicle. (unless you have the spare room in the trailer) The battery drain is minimal.
Hope that helps.
1968 26' Overlander
2019 RAM PowerWagon TV-Petrol Hemi
WBCCI # 22342