Oooh, another thing to think about next year, Melysion, not to hijack your thread, but you'll have to tell me sometime how you manage to keep Toby indoors with no screens on windows. Have you installed some or does your house have them?
I like the idea of installing a cat flap and attaching an enclosure. We had an enclosed porch when we lived in TN and it worked well for the cats to get fresh air and be outside. We just had a cat flap installed so they could go in and out as they please. What about screening instead of chicken wire if bugs are a concern?