There are places, as the above post mentions, that treat career CFI's better than your regular FBO can. There aren't many of them, though.

Another way to do it is to work at a large flying club where you can free lance for $40/hr and set your own pace.

Also, buy your own Cessna 150 and start your own little informal flight school. I think, in the right place, a guy could do alright in that situation.

I hate to tell ya, though, I don't think your average school pays more for the guy who sticks around a while. Maybe a little, but not enough that it would matter.