Bow Filler Seat & Weight

I have a 96 Sunsetter LX and would like to add one. Where can I buy one or do I have to have it made somewhere?

Also, I have a locker sac and was wondering how much weight I would need to add in the rear to make a difference. I'm old enough and my son is young enough that we don't need a HUGE wake, but I would like a little more wake than the wedge provides. It's amazing how much less height I get than I 'feel' I get when going w2w after seeing myself on video.

Thanks, Greg