So, just viewed the video from Scotland and have some comments.
I would get rid of the control horns asap and replace with quality ones (nylon). HK uses the absolute cheapest and brittle ones on the planet. I have seen them brake just by staring at them (old goat trick
).
Also, I have installed a 1 x 5 mm flat cf spar to the elevator and a solid cf spar inside the very thin wing spar, for support.
Other than that, you have covered just about every recommended mod that the net has to offer.
Well done.