Hi Mike
You may want to consider this as the simplest way to go, and that is to get one of those ipod type thingies and record your own regular backing tracks. This way you wouldn't have to shell out the extra bucks for another keyboard, and you could even make it look like you actually were playing if you thought that would make a dif in your performance as compared to looking like you're just singing karaoke style to a recording.
My wife got one for me for Christmas with this in mind.
Or, you could use your laptop for the same purpose along with using it for lyrics and sheet music. Remember the free Virtmus program that is along the same lines as MusicPad Pro.
For you, as you don't use powered speakers, that would be the thing I would give the most consideration, because if your pa head goes with no backup you're dead in the water.
I know you're using Peavey PR15's. Maybe a pair of powered PR12's which are now only 35 lbs along with a Behringer or Alesis mixer would be something to consider. That way even if one speaker would go, you still have one to do the show.
Best
Scott
http://ScottLMusic.com [This message has been edited by Scott Langholff (edited 01-02-2008).]