I just want to offer my fulsome sympathy. I've had a nightmare time with those bottom wings, on two builds; I pulled the fat out of the fire once, but was beaten the other time.
This won't help much, I'm afraid, but my impression was that it's crucial to get the front two fuselage/'cabane' struts right, ie. exactly the same height. The problem, as you've probably noticed for yourself, is the internal engineering which makes that quite hard to achieve. Then the rest of the strut geometry is thrown out of alignment.
Good luck...
Mark