Hello.
Polyspan is good, many times stronger than paper, but still not so puncture resistant. And sanding it can be a pain in Arsch.
For solid wooden surfaces, there is allways an option, like Japanese tissue or light weight Modellspan paper. Or this carbon stuff that everybody's talking about.
For open structures, how about the polyester "Ripstop" fabric that we use in Free Flight? Many sportsmen have allready abandoned the polyester paper, especially in F1A, because it's too fragile.
The material that I use is about 32g/m2, a bit less than an ounce/sq.yd. It's extremely strong, I think it's originally ment for technical clothing. There is also another similar material called "Icarex". It's about 37g/sq.m. It's easy to get from kite suppliers. The Japanese stuff that I use is just slightly better for my use, but in C/L it propably won't make any difference.
Basically it does not need any sealing after shrinking (with heat), but we normally brush 1...3 coats of well thinned dope and then wet-sand with #2000. That's because the new airfoils work better with smoother surface. But basically you could start with primer coats right after covering. The stuff is glued in place with thinned contact cement. The glue is brushed to where you want it to stick and let dry. Then the fabric is put in place with a covering iron and heat-shrinked.
Lauri