It is true that photographs can add complex details in tight places, but it is tough to pull off convincingly. Usually it looks good from one viewpoint but not others. As an alternative, don't overlook using "mountain flats". They can be pretty effective in limited spaces.
This rock face is only about an inch thick. It is made from thin strips of ceiling tiles hot-glued together:
This is just foam-core--even thinner:
A lot going on in a very small space...
Flats can also make a good transition between mountain work and a back drop:
