I can't help with your question but is it possible for you to get a smaller cage for outside use for when you are at home? Do you have your own yard and any grass? We have 6 piggies (all non pregnant females) and keep them in a very large bird avery with a cement floor but we do put them in 2 smaller cages a few times a week for them to sun bake and eat the fresh grass which they love. In summer because of the heat we freeze bottles of water so they lie against the ice to keep them cool. I know they don't store VitC so you can give them a supliment but I don't know about VitD which comes from sun. Most piggies in other countries aren't kept outside (due to the weather) so I assume no sun must be ok for them. I joined a cavy forum years ago and got my head bitten off from almost every member from having mine outside.