Thanks for your quick replies!!
The area around the barn, about an acre, is electric taped.
My concern is that I like to turn the horses out in the front field - 4 acres of good grass. It just has a barbed wire fence around it. I know, not so great, but the grass is excellent, and I've never had an issue with other horses. Most of the fence is hidden by brush and trees, so the horses tend to just hang out in the grass and eat. I'd really hate to not make that available for a hungry draft.
I'm worried that I'd end up with a mud-hole with little grass right around the barn if that's the only place I can keep her.
I have English Mastiffs (draft dogs!) Their size makes them "bump into things" too, and the tails are like baseball bats! No delicate things on tables at my house!
I guess it totally depends on the horse and what her tendencies are. I'll ask the current owner what her experience with the horse is with respect to fences.
Other comments are sincerely welcome!!