Clear doped linen?

I've never tried it myself, but I have a friend who used to build armor dioramas, and when he needed to represent something that was cloth he would use tissue sprayed with diluted white glue to cover the area. I suspect that it was the wrapping-type tissue and not facial tissue. Once the glue dries it can be painted any color you want. Probably a bit of work for a biplane wing, but it might give you some very realistic-looking results.

I picked up some Polly Scale "doped linen," and it is VERY green. I used it for the sidewalls in this cockpit. For the exterior, I mixed Model Master "wood" and "flat white." I probably could have gone lighter, but I think its better than the Polly Scale.

Given that there are no color photos and any samples of early aircraft have aged 80+ years, I'd feel free to go with either the Humbrol or the Polly S, which I used on a Fokker Dr1 and was given good remarks on the color.

Testors has a "sand" color that some folks like to use for CDL.

Regards,