A very small tank will be more difficult to balance...that being said, if you are committed to this, doing lots of W/Cs will help stability if the water is heated, aerated with same ph & other parameters.....
Bare bottom would be best for cleanliness...add some interesting pcs of driftwood, perhaps with some plants attached for looks (for ppl, not fish). For myself, I like the Aquaclear filters, easy to use & easy to clean....then I add sponge filter(s) & airstone(s)...add heater & lights....there's lotsa ideas for the back of the tank, paint, foil, plastic, homemade nature scenes....do a forum search... tankmates will be limited, but corys or plecos may help with cleaning....
Major limitation will be the # of discus....4 to 5 at the most & with lotsa W/Cs (usual # considered to be 1 discus to 10g water)..........remember W/Cs..W/Cs....W/Cs....HTH, JMO,
Dottie