Alex, this is a prototype and earlier in this thread you mentioned that you did not use the very lightest balsa so all things considered, your finished weight is very respectable. Maybe you can save a few grams next time you layup the composite parts? I believe you said that the plywood used in the frame was 1.5mm regular plywood... does someone (even if it's from overseas) make 1.5mm lite ply? Go test fly it and enjoy the fruits of your labor! Once you get the incidences right and make any decalage changes to minimize mixing, you could certainly offer short kits for sale to help recoup your development costs....
we are entering the winter building season and the marketplace is crying out for a reasonably priced, well-engineered pattern kit!!!