ORIGINAL: BaldEagel
Using 28gms/onz = 119.785onz = 7.4866Lb
That is very light. I think the Yak 54 72" almost weigh that much. Under 15lbs RTF sound very doable. Composite construction typically shows its benefits more at the larger scale.
I agree on the "no former" is better. The builder can always add reinforcement trusses if he feels the need. Plus it allows the rudder servo to be placed where ever suits the particular install with only the necessary bracketry and weight added. Unless you use a very lightweight engine, you'll probably put the servos in the rear anyhow. I really like the rear hatches. That was one feature I wish they had done with the Yak.
What engine are you planning on using?