Hi Jerome -
I agree, while the pen is an excellent idea it seems your little girl is quite the smart one and that either a real x-pen lid (that can be latched on) is needed or another option is needed.
A safe place is key to protecting your little girl. When I was in Jr HighSchool (almost 20 yrs ago) I was doggy sitting my gramma's Chi. Taffy stayed in my bedroom with my dog while I was at school. However, one day I came home and somethng was wrong - her face was all swollen. I couldn't get a hold of anyone to help me so I ended up getting to the vets office all on my own. Thankfully they were good enough to help her even though I had no way of payment at that time. It turns out she had somehow gotten behind my desk to a power cord and chewed on it, we were VERY lucky she survived. We thought my room was completely puppy proof, but she proved us wrong! It was an ugly learning experience but one I will never forget.
I take puppy proofing a room and home to extreme measures now and if a puppy can not be watched, even for a few minutes, then they go back to their crate or the leash gets put on and tied to my belt.
As to how much space is needed, here is a picture of a huge crate that I used for my girl LaVie when she got really old and could not be left loose. Her pee pad went on one end, her crate in the middle, and her second bed in the far end. She had food and water available at all times. On occasion she would step in her poo but not that often. I would clean her crate and give her a new pee pad at least twice a day, sometimes more if it was needed. The crate is large enough for a Great Dane, we called it LaVie's palace.
LaVie crossed the rainbow bridge when she was almost 16 years old. I've also included a picture of her.


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tabitha
Kayo, Kahla, and Dante'