Sounds like you want a Lib Tech Hot Knife, but at your weight you're going to have a hard time making it flex... They don't come in wide. The 159 has a width of 25.5 cm (10 inches or so), so you'll probably be able to get on it, depending on your stance angle, and your boots... Might have, at most, half an inch over hang on each side.
I've looked up, and still don't understand, waist width. Right now I have a 155 burton flying v with a 256 mm "waist width". Could you explain?
And the hot knife is what I've been eye balling, but like you said it isn't in wide..so I've been back to browsing.