I just want to add that cold weather is really not an issue here in South Florida.
I can't imagine training a horse to pee and poop outside like you would a dog...I mean, a dog poops twice a day, and I let my dogs out a minimum of 3 times a day to pee. Horses poop...what would you say, about 10 times a day? And probably pee that much, too?
Ok, I am considering keeping bedding out of the stall. Like I said, I do that for the minis, but they rarely go in their stall and never really did (I did have shavings in there at one point), whereas this mare seems to like her stall, so I feel it might be a little mean to keep it bare. I will decide, but thanks to everyone for their comments and input!