Then there is the add in issue of how much is your time worth? Lessee $3000 vs say $2000 for materials and tools + a bunch of your spare time + the chance that it will fail. Hmmm. I would likely just buy the known good set of new covers, then go fly with confidence.
My advice is to stay with the original design by using sails....the aircraft is designed for them.
You will gain nothing by trying to change covering methods other than sleepless nights,an empty bank account and a plane that is not airworthy.
Bite the bullet and call Sandy or Brett and spend the money on new sails.
I could have changed covering methods but it just wasn't worth the hassle of redesigning everything or the money it would have taken...so I sewed up my own sails with the help of a friend that made sails for a living.
I think they turned out quite nice....
Stick with the original Dacron covering.Your costing analysis has a lot of holes in it. Just the painting will be a PIA and a lot of work and wont look as good.As others have mentioned, resale will be a issue.