I started in a very small sunny area after reading Dave's article. I have a subdivision size backyard with mostly large shady oaks, and I also have varmits and the occasional snake. I don't have a dog or cat anymore. I have a "grand dog" that visits frequently, so I figure he keeps anything that might hiss or slither out of my yard. I remember that you have dogs, so I would think they would keep anything wild out of your garden area.
Right now I have a huge screen on top of my pile, held down with pots, to thwart the possums and armadillos from possibly digging in it for food scraps. If it wasn't so wet out there, I'd go uncover it and take a peek. Dave would probably be better to ask about varmits, but I've not had a problem. I was worried about rats coming in from the greenbelt, attracted by food odors. That hasn't happened, that I know of.
I used some downed and rotting limbs from the greenbelt and from the lake that have seemingly disappeared into the soil. I made a couple of limestone paths so I wouldn't have to step on the garden area soil. Mine's a mini experiment! Just waiting for spring now.