I have a 4 year old that has developed excitement around camping, and when backpacking was described his first question was "Can I go with you?"

Has anyone here run into backpacks and other gear for young kids? Don't need a lot of room as most of his job will be getting from point A to B, but I am curious on what is available. Currently he has a mini mule from camelbak for a backpack, and his sleeping back is decidedly not for backpacking.