Love your work.

Here is the glue that I used in the end. It welds the pieces together so well, that the parent plastic will break before the joint lets go.
Can't ask for more than that. I'm betting that the cowl is polystyrene.

I called in at our RC gliding club on the way home this afternoon and created a lively discussion among the members.

The consensus was the same as yours, so I'm going for the position that gives me the right 'look' and adjusting the motor afterwards.
Everyone's efforts are most appreciated.
Cheers