EUREKA MOMENT. Struggling to get to sleep last night. Mind wandering everywhere (cars mainly), then realisation dawned, so this mornings Home Schooling is Geometry. Now focus, this isn't easy to put into wordsWhen the door opens, it is VERY close to the body before the door leading edge enters the large concave area. - And I mean close. Door is not yet painted, and literally, just the thickness of the paint will mean I have contact I don't want to move the door back more, as already the gap at front to the body is close to twice the width of the gap at the back, ( but it doesn't look too bad and they are parallel).
The clearance between door front edge and body as the door opens is dependant on where the hinge pin is in relative terms ( You've got to remember there is much slot adjustment between the beam and the door skin, so the 2 can be moved independently). In short, the further the pin is away from the car body, the more the clearance as the door opens. Think of two extremes ( both impossible but it helps see the reasoning).
Worst extreme : If the hinge pin was hard up against the body shell, the radius to the door front edge would be much greater and it would track a wider arc as door opens. Result - Very quick contact with rear of front wing.
Best extreme : If you could bring the pin out to a position coincident with the door skin, not only is the radius smaller, but the swing arc moves immediately away from the rear of the front wing and impossible to have interference.
So, if you think in plan view, the smaller the angle created between a line created by the hinge pin and the door front edge, to the line of the outside door skin, the better. In the worse case above its probably about 30 degrees, In the best case it would be 0 degrees.
This also explains why SJ sell 4mm thick hinge plate shims Firstly 4mm isn't a shim in my book, it's a spacer, but that aside, it lets you do what I describe above. I never understood until now why they made such a large spacer, as the adjustment between beam and door skin allowed the same adjustment. Now I understand.
Of course, bringing the beam so far "out" will require similar thickness spacers between the window frame to beam if you want to stay dry and still hear the radio.