Well, I just found these: https://www.alibaba.com/product-detail/Customized-powerful-magnetic-usb-5-pin_60628607437.html
If I can buy less 5000 of them, that might just work
And I would need to build some sort of swivel system like the magnetic car couplers. I was thinking maybe on top of the cars for ease of building. Definitely need to find some ideas on that...
Not entirely sure yet. Basically I'll have five wires, two for power, and three for data. Leaving my options open for now.
For my LEDs I've got one wire (three reall, vcc, ground, and one data) addressable strip, but I'm also looking in 1-wire devices.