Craig,
If you just got a WW boat and want to put in a back band there are alot
of ways you can do it. I retro fitted a IR back band for my first WW
boat and it was great. That is untill I started to paddle it and the
rotation of my torso against the backband tore my back open and made it
very painfully to paddle.
So I would advise on buying a back band putting into your creek/play
boat. For your WW boat I would glue some foam on the back of your seat
to push against.
Take care and good luck with your outfitting I know it is a pain.
Rodney