Sometimes things come to he who waits.
I hadn't had much time to progress and then I get a pm from a member who has picked up an unused resin tailplane for the 1/12 hero. I asked for a couple more pics and reference dimensions so I could recreate it exactly.
Turns out dimensionally they stuck to whole or down to 1/8" dimensions since it would make it easier to scale. Also the angle on the lower front section lines up with the top corner, again,makes it easy to replicate.
Using the correct size tailplane to what I had showed me I was slightly over scale. Basing the top of the engines as a hopefully correct size reference relative to the tailplane I had to adjust down by 5%. Now the overall length comes out within a fraction of 15.75" the correct size for 1/48th, 63" at 1/12th for the hero.
With the tailplane itself I wasn't far off overall, slightly too much angle back, and the rear kink was a bit too small.
Didn't notice it until I took this screen-grab but the angle of the lower rear of the tailplane now matches the angle on the rear of the body engine section
Thinking they may have well used whole or fractional measurements for other parts I scaled to 1/12th and got a confirmation that I must be pretty damn close to correct.
Other main dimensions work out such as 13" for the width of the front of the engine section and 13" for the main engine section depth, 31" main wing to wing end width, 3.5" depth of intakes from bottom wing etc. Kind of wish this had occurred to me before as it would have helped me size parts.
So next to rebuilt the tailplanes with the correct profiles.