personally I think it will be a struggle but its probably doable.
Base it on 4 breakfasts, 5 lunches and 4 dinners. I think I'd run the fridge as a freezer and get a small esky to use as a 'fridge' of sorts during the day. Take the day's rations out of the freezer and allow them to defrost in the esky. Put a day's supply of drinks in the esky and they will chill with the defrosting rations. Premake meals that will keep and can pack down easily. Pasta sauses and fried rice can be cooked and stored in zip locked bags and refrozen. Vacume packed or cryovacked meat can keep longer. I'd even consider precooking your meat so it can be easily reheated. Also marinading cold meat can help it last longer. Take plenty of canned or dehydrated food. Pack fruit and vegies that don't need refridgerating to keep like potatos, onions, root vegies, apples, oranges, etc.
If you have one of those thermal cookers, you can cook meals on the go without having to keep them refrigerated during the day. Just get the meals started in the morning and you'll have good hot meals ready at the end of the day.
Some of our staples that we keep in the van ready to go:
Tiny Taters
Spam (slice up and fry. just like bacon...!)
tinned fish (tuna and salmon, can get flavoured varieties)
baby carrots
corn
beetroot
pineapple
creamed mushrooms mixed with soy or terriaki sauce makes an excellent gravy
make anti pasto from preserved food like sun dried tomatos, roasted capsicum, olives, artichokes, pickles, onions, etc.
instant asian meals like sui min or similar are great for a lunch on the run.
flavoured packet rice
There's probably enough variety there for 5 days
good luck