Well, I've punted the plan for cable rails on the Leadfoot Speedway; I just couldn't get consistent enough slot depth for accurate installation. Since I don't want magnet racing anyway, I've gone back to the copper tape that I've used before. I only anticipate using my own cars on this track, so here's what I did to get current Auto World tjets running on copper.
Cut strips of .005" brass about .09" wide. It cuts easily with scissors, and even though it curls, it flattens out well with smooth-jaw pliers.
Bend a small hook at one end.
Remove the stock pickup shoes and springs. Hook the strip over the front of the chassis and cut it to slide under the stock conductors. Tack-solder in place.
Solder #3 (.1") braided solder-wick to the upper part of the hook. Hold all but the very end of the braid
with pliers so the solder doesn't wick down the braid
(as it's supposed to do). The solder-wick is available from any good electronic component supplier.
Bend the braid
around to the bottom of the chassis and cut just behind the guide pin. This length will allow the car to slide, but won't short the copper tape if it gets completely sideways.
The cars now work great on copper. Yes, each car has to be modified but it's easy and cheap. And it's reversible if you want to put the original pickups back on.