I would not trust PVC unless you use very large diameters, which negates both the cost and weight advantages. If it's light and cheap, it is not very good at foiling a determined intruder. Dogs are the worst you need to worry about structurally, then use hardware cloth at least 18 inches around the bottom to avoid possum attacks.
This is the type I use, which I believe to be predator-proof (maybe not for bears, but we don't have anything bigger than coyotes and dogs to worry about).
In PA, they do not work for winter, I remove the tarps and let them sit unused until spring.