Help: 3:5 scaling on the Senkawa 117‑p dragon throws off the tassel valley fold

Been tweaking a Senkawa 117‑p dragon (the one with the twin‑tail tassels) all night. Trying a 3:5 scale on 120×200mm Saito #3 paper, and the valley fold at the tassel base just wonky – pops open when I flatten the rear wing.

What I'm seeing:

• Initial squash fold on the wing matches the diagram, but after the first squash‑push the adjacent valley at the tassel root creates a micro‑crack.
• The 0.6mm pre‑crease I scored with a bone folder is barely visible on the 30gsm paper, so the paper creases rather than bends.
• When I dry‑press the tail for a few seconds the pop recurs.

What I've tried:

1. Double‑scoring the tassel valley (lightly on both sides) – nothing.
2. Using a heavier 48gsm Sato sheet – the pop goes away but the whole model feels stiff.
3. Adjusting the mountain‑fold angle by 2° on the rear wing – still pops at the tassel.

Anyone hit this exact issue? Any tips for reinforcing that valley without ruining the delicate curl on the tails? I'm open to a bit of glue on the inside or swapping the crease‑line orientation, but keep it light. Feedback appreciated – especially if you've kept that fold tight on a 1:1 scale.

• SubstantialApe137