Thank you Lynn,
I would like to also tell all that these little shallow plantings are very realistic in the long term. Any very shallow container will work with some plants that I have been working with for over 30 years.
The secret is:
Super saturate real unprocessed Spaghnum. Ring it out with your hands to as dry as you can get it. Pack it in as tight as you can get it to a 1/4 inch depth. I grow some Bonsai trees in the same.
Add the plants and spread the roots over this compacted Spaghnum, and then continue to slowly and tightly add more of the same around and over the plants. I use the back and front side of forks and a dowel in this process.
Small Bromeliads, certain difficult succulents, (including the plethora of Haworthias I have never seen reproduce better, and thrive in this situation;...some of which I have grown in 1" deep containers this way through the years) and of course all Tillandsias work this way.
The Spanish Moss is a dressing only, and is a living Tillandsia also. Its not the growing medium. Fish Emulsion from fermented fish grinds in containers (costly) or fish water from your tanks or pond cleanings are the star fertilizers used sparingly. I will whisp the Miracle grow (liquid fertilizer of choice) over them rapidly on occasion too...
Go ahead and experiment with these techniques I've just shared. You may be surprised!