TechStuf

Your plan appears sound, with a couple caveats. I'd make sure you cut the plastic for a good smooth fit and see that all edges are completely sealed. Also, there are flexible fiberglass spars known to those of us familiar with the sport of Hang Gliding, called "battens". They are used primarily to provide consistent shape to a soft wing during flight, also preventing flutter and premature fabric failure. An adaptation, I believe, would help in your application. Perhaps by using clear 'packing tape' by which to secure a few of those cheap, long fiberglass rods such as used on children's bicycles to support flags, longitudinally along the underside of the plastic sheeting, you will avoid much of the chaotic buffeting that otherwise occurs. If you implement this idea, I'd go ahead and pad the tips of the rods.

With good quality plastic of sufficient thickness, and a few 'battens', you should be good to go!

Just how far, however, is a bit of a 'variables' dart throw. Better keep a bit of extra plastic and tape on hand.


TS