Newbie Needs Advice re: COOP DIMENSIONS, Please Help?!
You are correct about needing at least 64 square feet. 8x8 is a decent sized coop, and may be too big and heavy to move by hand. But a coop on skids could be moved by a lawn tractor. I would make the skids out of 2x4's with both end rounded up so they won't dig in when being moved. I would build the coop out of 2x3 framing, as this will save weight and money over 2x4's, but still be big enough to drive nails or screws into without splitting. Another option would be to build the coop on a trailer. A used 6x10 trailer would work, you could even use a Harbor Freight 4x8 trailer under a 6x10 coup.
Building an 8 x 8 x 6 high movable tractor will be heavy if you want it to be a covered coop. Tractors to be light are just day use items made of light netting and chicken wire. A frame of wood or metal. To be a coop, it is possible, but needs to be strong, so as to be resistant to predators. That equals HEAVY. IS THERE A REASON YOU NEED A TRACTOR TYPE COOP??? If you need something movable, can I suggest getting a travel trailer and converting it into a coop. These can be had for low price to free on older models. All you need to do is modify it. Not sure what your circumstances are and how much work you are able to do yourself. Here is a link to a thread of just something similar.
WISHING YOU BEST