That trailer is a really innovative idea to make a tractor-type coop. The rudimentary instructions about it are in a reply to someone's review, but should be part of the article. We need a little more detail how you built this as it's such a great idea!
1. Built a frame and internal supports for a floor and it was eyeball leveled with 2x8s
2. Screwed down a 1/2" plywood floor.
3. Bought a Super Heavy Duty Tarp and stapled it over the floor to prevent rot. It has worked for the past 3 years thus far.
4. Went to the amish lumber mill and bought thick 8' random type slab wood.
5. Measured an old external door and built a frame for it in the wall.
6. Went to Lowes and bought two small windows and built a wall frame for them.
7. Built a frame in the back wall for a low horizontal door.
8. Built a frame for the winter run on the side.
9. Then I closed it all in by screwing down the Amish lumber side by side until it was completely enclosed - nothing fancy.
10. Put on the door and painted it.
11. Then I decided we needed a winter run so I added two posts to the outside to create a 3 sided enclosure and a sloping roof topped off with a polycarbonate roof. Does not generate heat in the winter, but gives the chickens an area to scratch around in all winter w/o the snow.