I didn't do the clarinet in exercise 1 because, as you said, it has dynamic control in all registers.
In exercise 2 I was going for something bouncy, happy, and I imagine the strings pizzicato in the background, playing happy bouncy chords, possibly major ninths.
In exercise 3 I was going for something calm, and peaceful, so I used a major seventh, putting the B in the clarinets so it didn't stick out like it would in the oboes, or in the soprano or bass. I only used standard orchestral winds, non of the extras.
Thanks so much for doing this Michel, I've enjoyed doing these, and look forward to the next lesson