My 3ft tank is planted with Vallisneria, Amazon Sword, Anubias, Banana lillies, and Pongol ( a type of grass), Java moss, and duckweed on the top. And some other bits and pieces I can't remember names of. That tank gets light 8 hours a day. Single triphosphore globe.
The light doesn't bother my axies, but that could be because I have lots of shady spots on my tank where they can hide. The duckweed helps shade the tank, but once that stuff is in your tank you'll be scooping bucketloads of it out for the rest of your life.
I hear crypts do very well in low light, Although I'm unsure how they will stand up to the axies.
Everyone recommends elodia, but I can never get it to root, and my girls rip it to shreds, and my tank ends up looking like a tossed salad.
Just go for tough plants, nothing lacey or delicate.
There is a post in the gallery section called "Just a few funny photos" - shows my 3ft with all its plants.