Dope doesn't weigh much so you can continue to add a couple more coats of dope sanding with 800 grit wet in between, or you can spray on Poly Spray from the Stits covering system line, still sanding with 600-800 grit wet, I have even used a high build euro primer over the cloth then sanding off almost all of it prior to topcoat. The safest way to keep it light is to dope twice Poly Spray twice and top coat.
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Bob