Java Moss is really easy to grow in low-tech tanks. As a result, it will probably grow like a weed and may be more maintenance that you want. There's only one way to tell, though, and that is to buy some and give it a shot. I think it would look nice in your tank.
Java Fern may also be an option. It can easily give the overgrown jungle look and has about the same requirements as Java Moss. Plus, it's easy and grows well.
A personal favorite of mine is "Corkscrew Val". It can be used to give a jungle type look. It's easy to care for, but requires moderate light to really take off. Under low light, you may be able to keep it going slowly enough that you will only need to trim it once in a blue moon (well, maybe more often, but you get the idea).
I'll look through some more plants and see if I can find anything else.
75 Gallon High-Tech Planted Community
3.5 WPG using T8's
Fluorite w/sand mix
Rena Filstar XP2
Pressurized CO2 w/SMS122
29 Gallon Goldfish
4" Red/White Ryunkin
4" Orange Fantail