My Guinea Pigs don't get a lot of exercise because we are pretty busy. Right now, we are getting on with the C&C cage and I was thinking that since one part of the Coroplast would be 6'' then I could take excess grids, build a playpen around the 6'' area and remove the couple of grids that protect the 6'' Coroplast and then put a piece of of excess Coroplast to keep them from going out during night. Anyway, I was wondering if that would be a good idea for exercise and playtime?