I'm still crawling around that Tiny Yellow House channel on YouTube, and found this cool thing:
The Junction Box Stash Spot.
Genius. But for extra authenticity, I would make one of the wires crawl along the floor joists for a while and then tuck it behind another wire. I think he's got a bare wire just so as not to spend a lot on his example.
If you're getting all basement-y, you could also do a fake furnace vent or sewer stack. That would hold a lot of big long stuff.