Okay, it seems these are refer to models with no open bays. What about a traditional build. How does this sound. Nitrate on bare wood. Silkspan, polyspan, docspan, silk, etc. Then, can I still use the zpoxy to prep the fabric, or use klasscote primer? Then procede as indicated?
No, you need a sealer for the fabric, and epoxy (glue) is not appropriate. I prefer non-taughtening nitrate dope (SIG), because it gasses off much faster than butyrate, and doesn't have any plasticizer so the adhesion is excellent. Seal it up until it is nice and shiny, then primer over that.
I would only consider polyspan at this point, it is very durable and requires far less sealing than silk. Silkspan is in-between as far as sealing goes but far more fragile, exam tissue is probably just not recommended for a variety of reasons.
The problem with this is that the primer will require extensive sanding, and while it sands really well, there is always a risk of going through and getting fuzzies, or all the way through and leaving a hole, is pretty high. People do it, but you need to be very careful. Whether it is worse that typical dope fillercoat (corn starch or zinc stearate/clear dope) on silkspan, hard to say. If I was going to do it, I would probably have to consider dope colors with urethane clear.
To be honest, I would, just myself, avoid open-bay construction, and at the end, the finished weight seems to be about the same as fully sheeted or sheeted foam - because while the structure might be lighter, it also requires much more sealing in the open bays. Sheeted (either way) also has much more reliable bending properties and is nearly unaffected by humidity or temperature.
Brett