ok, so I bought an '82 Ski Nautique 2001, finally, i've been looking forever. Now I am looking to put some weight into it. I've heard the best way is the put the weight on either side of the motor, but I want that room free for walking and moving around. Since the back seat is just a cushion I have been looking to replace that, and I saw the Fat Seats and the Fat Sofas. Figured if I got one of those I could kill two birds with one stone. The question I have is which one will fit better in my boat? Also how much should I fill it up, and with however much weight I put in the back, how much do I add to the bow of the wake? I want something that is very durable, as I plan on keeping it for a long time. Also do you have to fill up and let all the water out everytime, or is it possible to just keep the sofa/seat in the back filled up all the time? Let me know Thanks.