If you are grouping coaches
Consider....
Springing for lgb electrical ball bearing wheels, one set, not cheap, and the running a tether between cars. I tend to make the most often used car, like a baggage van, the power car. In days of old, with the starter coaches, i used the 3019 post car. The BB wheels are pricey, but, offer a lot less drag, especially on longer trains and grades and curves.
As mentioned above, Tethering and wire connectors, like the old marklin /lgb style plugs, or the new, are not convenient, but they work, and save a lot of cost. The loco with an outlet is cheapest. If you group, the loco can uncouple, run around etc.
While i understand saving money, the lgb metal wheels, even non ball bearing, with double plungers, are reliable and last years. Yes, they can flicker a bit. I mention the obvious because they are not fiddly, and that seems to be a consideration for you. Having rigged pick up on n scale and...z, and, a single lgb item, its difficult to do well. Harder with low drag.
Btw, There are also electrical plans for cars that use track pick up, and rechargeable AAs which keep the lights on when track voltage drops.
I imagine one could install track shoes, like those on locos. Havent thought that one out, and i imagine they would be rather obvious visually. Things that slide on the track have great pick up, and, drawbacks too.
Best of luck.