Just read one of your comments below, for the style blind u are looking for. You can buy a beaver tail. The largest hey have available to closely fit yours, then get you some square tubing, and modify to your specs. Ive got a few different buddies that have gone this route.
But if your looking for a diver style blind, there is a much better approach than the beavertail or avery blinds.
Feel free to p.m. me, we can chat and i will share some input/experiences.