I want to thank everyone for all their responses and input! I really appreciate all the advice! Here's an update on the two turtlies:
Dozer's Hibernation:
Per PHRatz's advice, I've decided to keep Dozer indoors this winter. I have a 55 gallon rubbermaid that I've set up for him in my office. While it is still warm outside during the day I will let him outside in the enclosure with Daisy, but at night (since the low is now in the 30's) I will bring him inside. Because he will be in such a small enclosure all winter, I'll make sure he gets some play time out side of the rubbermaid for at least an hour every day. As PHRatz said, this will give me the time to monitor him and make sure he is healthy enough to hibernate next year. Daisy will be hibernating outdoors. I've already piled TONS of leaves on top of their enclosure (which is now almost 2 feet higher than the rest of the yard) - and she has started digging down much deeper at night.
Plants for the outdoor enclosure:
I tried to find a low blueberry bush as suggested by StephF but I had no luck. I was told at numerous gardening centers that they are out of season. I purchased a few other plants in the hope that they would work out. I have a small Hosta (which will become dormant in the colder weather but grow back every year), a dwarf spruce (which at 12 feet full grown will eventually be too big for the enclosure), and an arborvitae (which only gets to be 2.5 feet tall). I thought I found the perfect plant with the Arborvitae... It's the perfect size, its an evergreen so it will survive all winter... AND it wasn't on the poisonous plant list I found on the California Turtle and Tortoise Club website. However... I did some more research on this little shrub and on other websites it IS listed as potentially toxic to humans and pets. (SIGH!) I thought my search was over!!! If anyone has info on the toxicity of this plant in regards to turtles, please let me know. I'll probably plant the spruce for now since it is sooo tiny - It looks like the Charlie Brown Christmas tree! 
Again, thanks everyone for all the great advice! I'll keep you updated 

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My Kids:
Jack Russel Terrier: Skipper
Miniature Pinscher: Bambi
3 Eastern Box Turtles: Daisy, Dozer, and Magnum (yearling)
1 Red Eared Slider: Rosie
1 Twist Neck Turtle: Lilypad
2 rats: Clementine and Elsie


- The only other choice at my local shops is pine, and I was told not to use pine due to its negative effects on the respiratory system.