Cage thinking about adding a level

Hi, so I have two sows and am thinking of adding a level either above or below. Thier cage is a 2x4 (approximately, I have midwest expandle)and they get along really well. Im just worried that their pigloo takes up way too much of their space especially since they tend to move it towards the middle and would like to move it elsewhere but not take it completly away since they love it. I was thinking of linking the levels with pvc pipes rather than ramps since they take up more room? I can't expand out I can only do up or down. I saw a picture of a hay bin at the bottom since Zoey likes to burrow (she tries to burrow with her paper bedding in the "litter box". Im a newbie at the whole cage building thing so any suggestions would be a HUGE help. If you dont get what I'm saying or need more pictures please ask ill be more than happy to add more.