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I have a coleman xtreme 28l that i got for a 24hr ultra i used to do once a year where you setup a tent for your "home base" at the start/finish line between laps. I'd camp friday afternoon to sunday midday and if i put my perishable food in it with a couple of bags worth of "party" ice from the shop (no freezer) on the friday morning before I left there was still a surprising amount of ice in it on the sunday, enough for me to still have a cold drink after I packed up.
spent ages looking at Yeti, Pelican, Icey-Tek. Then ordered the smaller version of that Coleman.
It's arrived and appears no better than you would expect. Somewhat regretting not digging in for at least an Icey Tek
https://www.coolboxesuk.com/
However I dare say the Coleman thing will do the job for the time being.