Since I am pretty sure that pioneer doesn't make an extension cable for the ipod connection bus, I would think a dock connector extension cable like that is exactly what you are looking for. Hopefully someone on here can find one a bit more reasonably priced for you though.
One thing I just noticed, that one doesn't support video. I wouldn't mind, but I hope that isn't a dealbreaker for you. I can't seem to find any other extension cables anywhere. I would have thought there was a market for something like that.