Hi Brian,
This forum isn't providing Inkscape support anymore, since the new forum opened on the Inkscape website:
https://inkscape.org/forums/ I can answer your question, but I might be the only one here. You would get a lot more input in the new forum.
It is theoretically possible to do that. But the quality could end up being so poor, that it would either take a lot of work in Inkscape to improve the quality, or you just wouldn't want to use the result. I think it would take less time to find a matching font.
The whole effort depends on getting a high quality scan from either a photo or scanning the train itself.
But.... How large would the decal be? I'm thinking model train, it can't be much more than an inch in size. But you couldn't really see text anyway, that small. So it must be larger?
It sounds like you're on the right track (yuk, yuk
) using Trace Bitmap. That's what I would do, if I wanted to try it. But what do you mean exactly by "did not work". I would need more info to be able to help with that.