Which fridge make/model? And what battery(s) do you have? There is a small 3.3 cu ft standard and a bigger 7.7 cu ft. option, both 12v-only types Either way, you will definitely need to recharge batteries during your stay. I couldn't find any power consumption specs for the Springdale 12v fridges nor the size of the standard battery(s), so can't give a better answer. Think in terms of using a generator to recharge the battery daily rather than running direct from the generator all day & night.
What size battery does it have? Trailers that size typically come with a single Group 24 size 12v marine/rv deep cycle (unless you have added the Solarflex option).
For a 5 day stay, you will also need to replenish fresh water and dispose of waste water. Think carefully about that - you only have 21 gallons of fresh in your tank and storage for 30 gallons each of gray & black waste. That's probably only 1-2 days worth, even with your tent camping experience. Having a water tap and toilet handy tends to inspire more consumption.
I suggest you camp in your yard or driveway for a couple days to get a handle on how you will manage water usage and battery power. Don't plug the RV to 120v power - pretend you are out in the boonies somewhere. It's also a great way to learn what items you need to pack. You will discover you need certain items, maybe a corkscrew or a carving knife or whatever.
Springdale 1800BH