OldPhart - if you live in a rural area, see if you can find a failed 60 gallon fiberglass captive air pressure tank. It would be about the right size for the frame, they're tough, waterproof, structurally rigid, and have a lot of interior area for storage of sleeping bags, tent, fishing poles, etc. These used tanks are normally free for the asking, just pop out the interior air bladder, get a few extra cut off wheels for your peanut grinder and sketch out the desired cowl shape on the tank with a marks-a lot. A sanding drum on a 1/4" drill makes short work of radiusing the corners.