According to my new Poly Fiber manual the answer is 500 sqft for a Kitfox or Avid.
Did some interesting math. A 12"X12" sample of my current covering weighs 1.37 oz's. which works out to 40.78 lbs for fabric and paint. Poly fiber Med weight with UV coatings and Poly Tone top coat as per the book should come out at 29.4 lbs. Poly Fiber light weight with UV coatings and Poly Tone top coat would come in at 22.57 lbs. Oratex 600 with coatings comes in at 10.9 lbs and Oratex 6000 with coatings comes in at 15.6 lbs.