This would be an excellent coop for areas with large predators! While the welding DIY is not for everyone, it certainly makes for a solid-looking coop. I partly agree with the poster that the skirts would be better on the outside, but that would seriously cut down on the coop's mobility. Perhaps some hinged skirt panels on the outside, ones that could be clipped up while moving, would do the trick.
Overall, I REALLY like this design! Some minor tweaking might even make it marketable for high-predator areas. Nice job!