I’ve always imagined that it would be really neat to have a private sleeper car and get it pulled around the US (maybe even Canada) as part of a freight train. It could go places where Amtrak doesn’t, at times which might be more convenient for me (in accordance with freight schedules, of course). Where might I be able to find such a coach for sale or lease? And would the freight locomotives be able to supply electricity to it, or would I also need to arrange for a generator to be on board?
Biggest problem these days is liability insurance for your coach, and whether the railroad would allow carriage over their lines, as well as the lines they access en-route. They have reciprocal agreements with other railroads for use of right-of-way so it’s possible special permits would be required of each railroad you would travel over. Read that as $$$.
Coaches can be purchased as surplus from Amtrak and other railroads but they are pretty raw to say the least. Most need much reconditioning and then certification to be able to "ride the rails" again. Plus, there is ongoing maintenance with the car that has to be done en-route, so you need to either have someone who will do all your maintenance (journal boxes, brakes, bearings, compressors, electrical, heat and as you noted electric generation, traveling with you or somehow contract that to the railroad. And to each and every railroad that changes power units as you move from line to line.
If you should have a wheel flange go bad or a bearing go out, the railroad will not replace your wheel set. Your coach will be shunted off to the nearest siding, which could be in the middle of nowhere and you’ll have to arrange for all your repairs, including a crane to lift the car, etc.
Not to talk you out of what sounds like a wonderful trip idea, but being a realist, unless you are independently wealthy, you better have an American Express Black card with a big bank account to go with it.