You can also go to Sportmart and by a square Coast Guard approved flotation cushion(The one you would toss to someone who fell overboard) They are $10.00

I have a Trout Unlimited Kennebeck, which I love, but I need to sit higher in the tube. I noticed that by sitting on the floatation device, I not only sit higher in the tube(About 3 inches higher) but I also get the side benefit of equal weight distribution, so I don't slide forward. I secure it with bungee cords.

Lastly, it is nice to know that I have extra safety if my suspender type PFD did not deploy, and I could grab onto the cushion if I went out of the tube....God Forbid!

Hope this helps!

"RODSNAPPER"