Every filterless setup I have done has been quite easy. They have all been 10 gallons or less though. It's the same as other tanks, balance the lighting with the plant mass. You don't have to be low light but it's easier to start on the low end (CFL bulbs make this process much easier).
As others said, don't stock nearly as heavy. My guess would be 50% or so of a filtered tank. I have gone way less every time.
It isn't hard to do. The only issues are stocking and lighting (on a planted tank). I have had a few setups where I had really health fish, no algae issues, and had a lot of fun doing so. Much easier than high tech for me.