Ok got an email back from Charlie...Call up Bodyfloat. They fixed one up for me. I was probably heavier than you when I started riding about a 8 months ago. It works fine with the spring configuration he set up.
"We do offer, and recommend, BodyFloat for larger riders. That said, anyone over our posted chart weight of 260lbs voids the product warranty."
Little pricy for no warranty. I think I will wait till a heavy rider product is developed. It would seem to be a big market.