I use coco panels which is a lot like tree fern panels. These allow vining plants to climb up the back of your tank but they do not support bromeliads the best. Cork bark is your best bet if you are mounting bromeliads. I have a bunch of extra cork bark. If you want I can bring some down to the Indy show with me. I can also bring stuff like rice flour beatles or springtails if you need any. Later
Tree fern makes great backings. Rub some super soil into it before you stick it up and see what grows. You will get lots of nice ferns, and mosses in a few weeks. I use it in some of my thumbnail tanks. But I think I will be switching to spray foam . Darren Myer has a few spray foam backs with wood and some peat mixed in. You should see his tanks if you ever go to a WADS meeting. It makes a really nice effect and the frogs really seem to like it. So I'll let you know what I think later.
It's a brand of planting soil "Super Soil." You can buy a huge bag of the stuff at Home Depot for like $4. I use it in all my tanks, and its the only substrate so far that I've noticed the moss really thriving on.