You're almost going to want to overstock it bioload wise to get enough ammonia and nutrients for the plants with that small of a tank. I would think fish, snails, shrimp. The snails and shrimp would be small enough to not add to the fish space available but would increase the bioload a bit.
20g platy, , 2 x 10g shrimp, 3 x 20g shrimp, 7.5g shrimp and 1 great dane/mastiff puppy.
Sump Pimp #2
My Tanks and my shrimps