different cage idea

We recently adopted 2 peruvian piggies without doing any research into the idea, thinking they would be as low maintainance as the hamsters we used to have. Wrong of course, but after learning some of what it takes to have a happy healthy pig we are quite enjoying them (if only they wouldn`t pee all over us every time they are out!).
Anyway, the cage we originally purchased was way too small, and a couple of other ideas we tried were either too small or impractical. We had an unused cheap 3 shelf bookcase, about 3.5 by 2 feet, made out of some sort of wood-look laminate. I removed one shelf and cut a hole through the other, drilled a couple of holes to hang things, laid the thing on its back and lined it with scrap linoleum covered with newspaper and bedding. Its up on a crate about 2 feet off the floor (so our dog doesn`t climb in and squish them while she`s trying to mother them) and the sides are about 10 inches high.

I haven`t seen anything similar to this on any of the sites I`ve looked at, so I`m not sure if I hit on a really cool idea or if there`s some fatal flaw to my design that I haven`t thought of. The linoleum is covered enough they don`t chew on it and there aren`t any parts of the bookcase they can really get to to chew on, so as far as I can tell they are safe and they seem to like it. I`d like any feedback as to whether this sounds like a good thing or not.

Got a photo of your cage so we can give feedback? Thanks.