chemgodess1 right after I posted to the forum i thought about what I could do on my own. The 20 20 20 set I actually did as a 10 10 10 before I read your reply. When I lowered my legs back down to the ground I had to arch my back because the muscles were definately feeling it.
Another one i found is laying flat on my stomach, cross my ankles, and put my hands behind my back. if I lift slowly, hold and then lower it has the same geral effect as a back extension. If could actually do the shoulder press on the pole I would hook my legs around it and try doing a back extension that way because that just sounds like it would do the job.