I like this idea. Very nice use of stuff that most would haul to the dump or scapper. It is not huge chicken tractor but perfect for a small homesteader.
Have seen several of the cloth covered car shelters repurposed with used greenhouse plastic for cattle and other animal shelters. Best proof of concept was driving to work one cold winter morning and seeing a couple cows standing in the shelter and looking out at the snow. Door was wide open and there wasn't a track in the snow. Free range chickens love them too.