I am getting 2 doe pygmy goats and have a few questions. I already have my pen build...15'x30'....but need to build a shelter for them. What size should I make it? My fence is 4' high and secured all around. Do you think I will have any problems with them trying to escape? I plan to let them out each day....but the area that they have in their pen should be fine for the majority of the day, right?