That's a cool idea. I put broken things on my lawn, so that I can do a repair session under the influence of a "Focused" painting, all at once. On one game session, if someone I recognize is in my neighborhood, when I'm at work, I will take over that sim, so I can repair all my main Sim's stuff, before he gets home. Also, Dennis Kim takes care of my gardening, if I see him around. He can evolve my plants. Sometimes Nancy Landgraab waters my plants. I leave everything outside, so Sims in the area don't need to enter the house.
However, making a kidnap repair room sounds like an intriguing strategy too. I assume, if you leave food, facilities, a bed, and a computer with your repairman, he can take care of himself, while in your custody. I assume you can just drop broken items into the room with him. Of course, since my current approach is to become the best in every skill, I'm not sure I will be trying that approach any time soon. I plan to max my skills, before starting my first career.