Drilling holes behind existing walls/ceilings
I personally wouldn't go this route, as it would definitely be a "hope it works" situation. For starters, I would hesitate to drill through stud bays that I didn't have access to both sides of because there is really no way to be sure you wouldn't be drilling through something important, like existing wiring for example. Second, drilling the holes is only the first challenge - fishing a wire through 4 blind holes over 5 feet is no small task. About the only way I would see this is feasible is using the bit (plus extensions) to pull the wire back through after it is drilled.

If you decide to try this, don't use a spade bit.  Five feet worth of extensions going through 100 year old seasoned floor joists is going to be practically impossible due to the amount of pressure you would have to put on the drill bit and the number of joints in the system.  I would use an auger bit instead - that way you would have the bit itself pulling the extensions taut.