Planning for next season - Have some questions

Hi all - I have 3 layer hens I got this year I am thinking about trying a run or two of meat birds next year, maybe 10-15 each time. I would be setting up chicken tractors and have some questions about size - I am looking for something that does not need to be moved every day. Once a week would be ideal, twice a week is possible. I would be doing this on someone else's property that is about 20 minutes from my house. The property owner would be willing to contribute some labor but I don't think moving the tractor every day is what he has in mind. I would be setting up an automatic feeder system with measured dispenser and a water system capable of only needing weekly service. The owner would be monitoring the feed and water daily as needed.

I would probably be keeping the chicks at my house for the first few weeks or until they are able to stay outside. I have enough room on my property for a tractor that is about 4x8 and could be moved 5 or 6 times before reusing ground but after that they would need to go to they other property.

15 birds would be ideal, I am planning on offering 1/3 of them as a lease fee.

Any thoughts?