Some plants will cope if you keep the sg down to 1.005 or below. Try Java fern, Microsorium pteroides; Sagittaria, Spathiphyllum or Hygrophila though the extra turbulence and filtration might upset them (needed as you need a high amount of dissolved oxygen in the water. brackish fish are active and prefer a slightly higher temp which has a lower oxygen content. Surface turbulence will also help get rid of excess carbon dioxide and brackish fish release a lot of this due to their higher metabolic rates.)
As for fish, I am not sure of their compatibility with each other but fish suitable to this environment are;
Scats, Scatophagus argus; Indian glassfish, Chanda ranga; Archerfish, Toxotes jaculator (as you know); Monos, Monodactylus argenteus; silver shark, Balantiocheilus melanopterus; Molly, Poecillia latipinna; orange chromide, Etroplus maculatus; kribensis, Pelvicachromis pulcher; golden banded goby (bumblebee fish), Brachygobius xanthozona, Knight goby, Stigmatogobius sadanundio, half beaks, Dermogenys pusillus and 4 eyes, Anableps anableps
Archerfish require live food like flies, moths and crickets. They grow to about 15cm and can be aggressive.
Just did a bit of Googling. It looks like the scats and monos would go with them but they will eat smaller fish.
Have a look here http://wetpetz.com/archerfish.htm