What about power from a motorcycle battery modulated through an old-school Lionel #95 rheostat? It doesn't get much cleaner than that! The Santa Fe Flyer isn't too complex or expensive to experiment with. You could remove ALL of the factory electronics; connect the ground and center rail leads directly to the motor. For improved performance and a tiny bit of suppression, put a CL150 cap across the motor and add a double-pole switch to reverse polarity. The 5-pole DC motor has pretty low current draw and I doubt the resulting sparks would be detectable on a nearby VHF television. Pretty extreme, but if my choices were that or no trains, I would do the radical surgery as I've described.
Side note- when my brother & I were kids (mid-'70s before cable TV or hi-def), our layout was in the family room. We weren't allowed to run the trains when the football game was on, because it created "snow" in the picture! RFI was a problem with Lionel's original RailScope and all of those X-10 spy cameras that were so ubiquitous in the early days of the Internet.
A final option would be HO scale, again using battery power modulated by a rheostat. You wouldn't even have to plug anything into an outlet!
