make a bridge long enough that chests fall out of render distance, then double it
1 person gets on the donkey, turns on packet canceller and entity desync
1 person leads teh donkey to the end of the bridge, and then disconnects when theyre at the end of the bridge
person who is on the donkey turns off entity desync, and grabs all the items
the person who is still on the donkey grabs all of the stuff
the person who is at the end relogs in and grabs all of the stuff
the person on the donkey turns off the packetcanceller and then relogs
boom dupe