If you use the van primarily for day trips and not long outings, you might get by with a portable chest-type refrigerator like an Engle, Dometic or Indel-B(Truckfridge). It will just plug into a cigarette lighter port and you can use the space where the old fridge is for storage. They're not as level sensitive as absorption fridges and they're very efficient.
"Il Travato Rosso"
2015 Travato 59g