Rockershovel, I too have a door layout. "Real estate" is pretty valuable. So for example, rather than using the typical Lionel plastic dump bin, I use these Tupperware silverware single trays. I have a UC track right along the edge of the layout, then off the layout is one of these silverware trays painted black. Contents from dump cars go into this tray.
I've also made some "temporary" extensions using thin plywood and some bracing, which easily go in to the edge of the door (and can be easily removed), allowing for some additional items.
So on that thought, maybe... to add to your thought/consideration process, you could put a switch track on the edge of the layout, with that track going to a temporary extension, where you could be some sort of dump bin underneath the track for the operating hopper to dump into. You could place the coaling tower nearby. And as a added security, in addition to obviously having a bumper at the end of the extension track, you could remove the center rail, which would stop any locomotive from going beyond a certain point. It would also add a little ease to installation of the below track dump bin.
Another thing I do on my layout is I have some buildings/operating accessories that are always there. BUT I have others that I have purposed to be easily removed and replaced with another. This helps to keep the layout more interesting. For example, I have an operating tower that is part of a chemical loading facility. This tower is battery operated, so it is easily taken off the layout or put back on.
Also it helps to use a little imagination with a small layout. You don't have room for an entire industrial facility. So in my thinking, I have a loading dock which represents the larger industrial facility that you don't see (because it isn't there).
Likewise with the coaling tower. You could mount it to a thin base, allowing it to be on or off the layout. Then you could add some scenery details to this base, like maybe having a pile of coal that is glued in place.
I've also created little scenery vignettes on foam pieces that I get from stores such as Hobby Lobby. Like I have one vignette that has construction guys working. Or I have some scenery vignettes that have bushes and shrubs. Again these are easily relocated on the layout, or replaced with something else. I find ideas like this help to keep the layout from getting stagnant.
Anyways, just some thoughts for your consideration.
