Odd dilemma

As we realize that the days of putting the kids down on the floor and expecting them to stay put are coming to an end, I am beginning to seek out "babyproofing" items. Of course, one of the key things that we will need to get are gates - especially considering our hardwood staircase that is extremely vertical! My problem, though, is in trying to deal with our first "child" - Marley. She is almost 8 years old and is completely used to being able to go and do as she pleases. That means when she needs quiet time she goes up the stairs and into the closet where she has a blanket that she has worked to get in the perfect position. When she wants to eat, since she is on no particular eating schedule unlike our children and will NOT eat when someone is watching her, she goes to her bowl in the laundry room. When she is just curious about what is going on downstairs or upstairs or anywhere that she isn't she goes to check it out and often lets us know that a rabbit or cat or visitor of the human variety has arrived with loud and insistent barks (ok, maybe stopping her from doing that isn't such a problem). Anyway, with baby gates up on doorways and stairs, and to the laundry room so the kids can't get the dog food she will be trapped with us in all areas of the house. I have been looking at baby gates with pet doors, but then I wonder that if they are big enough for Marley than they will probably be big enough for a crafty baby. Hmmm, I guess the solution is to just make Marley deal with it. She can join in the frustration with Lance - as I imagine that he won't be too happy with the locks that I'm going to install on the toilets and cabinets :-)!