I am in the process of building a second level for our piggies, Oreo, Love, and Rainbow, and I am really torn on which direction to go. I was wondering if anyone has built a second level and used tunnels on the outside for access, without a ramp. If so, was it successful? They're babies, the oldest is 4 months. I'm hoping to maximize floor space for them since they are all boys. I have all the materials needed for both, because that's what I had planned to do, just can't make up my mind!