im guessing that when you say you film in 16:9, that your camera is actually shooting in that aspect ratio. what camera are you using?
i can shoot that way, but my camera accomplishes it by actually putting black bars on the video. keeps the aspect ratio, but doesn't allow for full-screen on wide-screen tvs (as far as i know, never tried it).
if you have an editing program its simple to create a black bar mask to overlay. as far as i know, you cant create a dvd version that will play equally well on newer AND older "dumb" tvs.
the only way to do this is to create two versions of your film, an anamorphic one and a regular academy one. that way at least people have the choice.