I currently have a large super pet cage. It is 39"x17". Now, I know this is really small, but my mom doesn't understand that guine pigs need a lot of space to live in. I tried convincing her into letting me get my guinea pig a larger cage that I would buy, but due to lack of space in my house, she said no. Im trying to give him more space by adding an upper level. Since I am adding on to a cage that has horizontal bars I was wondering if using grids as the floor for the upper level will be safe. I am going to secure them with special connectors and zip ties but their will be no support under second level, will it be safe? Also how large should the ramp be? One last question, I am adding the ramp so it will be going into a hole in the coroplast/grid (it will have borders to prevent sharp edges from grids) and there will be space for him to walk when he gets up. Has anyone done this before? If so was it safe/successful. I know this is long but thank you.