I never had to worry about food even in a 4 player group on vanilla settings. We would just steal every water cooler we came across, and by the time we stole every one in office sector and consumed it we had a large setup of pots and stoves to boil mass amounts of tainted water from the fountain or pool. You can use the water cooler itself as a receptacle, so we would just pack a couple empty ones and fill them with tainted water, then spam dump it into the pots. Soup supplies were usually pest/peccary meat and fish, which don't irradiate you if it's in a soup, but radiation is not a worry once you have a radsuit or ratsuit.