I guess depends on if you like gardening or trains better. I like the layouts that keep the trains more as the subject & try to keep things in scale as much as they can. :mrgreen:
The main issue is you can't let your indoor modeling experience and expectations color your goals and plans much as this is a whole new ballgame.
On the western themed model railroads, built in the west, they can get close by having the track wander through a pike of rock. That won't cut it for representing the great Eastern primordial forest, nor is any scale representation possible, and so we get into the realms of art. Short of bonsai, which take too much time and effort, scale trees don't exist, and so you have to work with what you have, using plants for thier color and texture to develop a feeling for the railroad in the woods without acces to much that is close to scale.
The moss that grows in my woods will be a great resource if we can transplant it and keep it alive.
I'm very skeptical of the concrete mountain approach, as I have, with the exception of some incredibly expensive zoo displays, not seen concrete rocks that were convincing. in any case, for Eastern TN. we would have to build that structure first, and then get something to grow on it. Ivy would grow there, but you would be constantly trimming it back.
I had asked my sister Judy, who was a biology major about taking cuttings from Ivy, and she said "Sure you can do that, but who would want to ; It would be like planting Kudzu.
In any case you cannot separate the railroad from the gardening, at least not in this climate, ant least not without spending a fortune on round up, and modeling a western scene. You have to skillfully make the one work for the other, or you will Have a lot of time and effort invested in a failure, either something that looks OK but doesn't run, or something that runs, but is a colossal eyesore.
Tom has a chance to make this work, since he is addept at making the forest/trees compromise (I err on the tree side every time), and his space is limited enough where he won't necessarily be overwhelmed (my gully is some prime real estate, but the time and other resources needed to concur it have never existed at the same time, I determined they were unlikely to ever do so, and have donated most of the goodies that I had collected, plus what my dad had retained for Tom's project.
Bill