I am totally against placing a cat in an outdoor run where they have no say in when they go inside. I don't see, though why an outdoor enclosure has to be built at all. There's your own bedroom and there's the guest bedroom. Plenty of people live in one room apts. and have cats (I did in my twenties- lived in studio apts. with 2 cats). I don't know Simba but it would be hoped that he would learn to get along with an additional family member, right? I think fostering is a great, even a super idea! IN YOUR BEDROOM! Simba would learn about cats and you would be doing what very few people are willing to do! My ferals who obviously were outdoor cats, are now terrified of the outdoors! They love the security inside, the human contact, the interactions with each other 24 hours a day! They love the windows, but when the door to outside is opened, they scamble for under the bed! For the most part, I'm afraid I agree with PIF and Rose-
Also, what's the rush? Do the honorable fostering and later, when you're in your own space, adopt, adopt, adopt!!