> installing batteries in DE engines
Sadly I think even installing infrastructure for local electrification would not get out of the starting gate, because you need to both modify all of the engines involved, as well as add infrastructure to every affected town with all of the predictable pushback from people who will react negatively the notion of installing a bunch of extremely high power, highly visible catenary on already-dangerous rail paths.
But fortunately we can take advantage of a useful characteristic of trains, which is that it's quite natural to hook up a car called a tender, normally carrying fuel such as diesel or (in the old days) coal but in this case would be a giant battery on wheels that's been pre-charged and positioned on a siding outside of town at the crest of any convenient rise, ready for connection to incoming freight trains. These can then switch off (or idle) their diesel engines and draw on the battery for power as it passes into and out of town. Obviously a fee would be charged, but towns have all the leverage here- it's not as if the freight can just take some other set of train tracks that go around the town to avoid payong it.
This has the benefit of being extremely easy to get by in on, as it makes very little demand of both freight train operators and towns respectively. operators need to add nothing more than a simple transfer switch to the engine (which may already exist) and for the towns, the same high power electric circuit as catenary, minus all the catenar, and located on a short siding safely well out of town. And of course a couple great big batteries, but they are mobile and can go where the yrains are, thus far cheaper than putting poles in the ground everywhere the trains run.