Well, I have applied the sanding sealer, done the sanding bit, etc. I can not feel or "see" where the fabric ends and where the body starts, so now I am ready to do the sunburst and paint the body cavities. Now, if it would only stop raining...
EDIT: I forgot to mention that it took way less sanding sealer than I expected to do this part. Maybe 2-3 ounces of the stuff did the trick, and after the sanding, it's quite smooth. Should turn out well.