We have a limited amount of space because a lot of our land is swamp/low ground. I'm wondering how big of an area would I need to keep 2 miniature horses? I would take them out for walks, training time, exercise, and fun grazing. But the winters here are severe and long, so they're may be periods in the winter where I can not take them out due to ice or other conditions. Could someone list the space in terms of feet that I can measure or count off, rather than acres? Thanks.