Great ideal and I really like it. The good tool balancers are actually pretty expensive. If you can find the track and these are easily available - would make for a quick easy solution.For overhead cable carrier I'm picturing unistrut with multiple trolleys to attach cables to.
View attachment 1702 (image Lowes.com)
This would go either parallel or perpendicular over the top of car. Cable affixed to a trolley say every 5 ft. So 2.5ft loops hang down or less when stretched out.
Similar to what @GDN shows above but with the unistrut track.