You could make a fake rock wall for the back and sides. It isn't very difficult, I'm making one right now for my 40 gallon breeder. It is made out of Styrofoam. There is a website for it, but I cannot find the link for it right now...maybe someone else can post it. Otherwise you could try googling 'homemade fake rock wall for reptile enclosure'. or something like that.
Hope this helps!
I had a foam background and had to remove it b/c the crickets were eating holes in it... if you feed your beardie in a separate enclosure then it would be fine.
I needed to cover the side of one of my tanks so my boys couldn't see each other. WalMart had some cool placemats that look like miniature bamboo for about a buck. I used double sided tape to stick it on. Looks nice, and natural. I think I still saw them the other day, so you might be able to find some if you're interested.
I currently have a 40G breeder for my guy. I installed ceramic tile in the bottom and I used the backgrounds sold at PetSmart to cover the back and sides. Looks great! But if you are looking for something on the inside like texture, you can certainly tile the inside glass...but you need to do it right so the tiles do not fall on your little ones. I used the aquarium silicone to put the tiles on the floor, but they fit very tight and there is no movement at all. You can always use smaller tiles in larger numbers to ensure they don't come down from the weight. With the silicone I used, I let it air out for 2 days even though it says safe for aquariums; I didn't want to risk it. You can essentially use any type of epoxy/silicone if you just make sure to air the tank out for a few days before introducing it to your beardy but do some research as there are many recommended brands.
Let me know if this helps and what decision you make. Would love to see your viv!