RE: Silkspan experience ?
I have covered small electrics but not a large plane. For this I use water poly (Behr satin) and koverall. I apply a 50-50 mix of the latex color and the poly to a piece of silkspan lying on a plastic sheet then lay it on the framework and quickly and gently pull out the wrinkles. Because the poly latex mix soaks into the balsa this part drys faster than on the open part and doesn't pull it off. Rub your finger around the frame to help it seal. Make up a small balsa frame and try it. It is quite strong under tension but punctures easily.
Good luck.