I have a tall 4 level shelving unit (very large) in the guinea pen but don;t know if I need to make it horizontal instead of vertical. My husband put in in upright but I think they will get in if it is turned horizontal with some legs on it. Any thoughts? They need a place to keep warm in winter ... correct? I am in PA... snow... Do you close them in a coop type like chickens or just let them in the unit with straw?