this is a bit embarrassing.
Anyway, here is the "working" script I came up with.
For accuracy I calculate the bearing differently for the first, middle and last image of a series.
Do you think the formulas are right?
May I ask you to take part in the GPled DIY-streetview project of mine?
We could really need some help.
I am available at janmartin AT diy-streetview DOT org for further information.