During the orchestration of a piano piece, sometimes there are fast passages (with long intervals) in the lower register, like that Villa-Lobos "Saudades das Selvas Brasileiras" passage:
Or this passage in Debussy's "L'isle Joyeuse":
However, for low-register instruments (for example, double bass, bass clarinet, contrabassoon, bass/contrabass tuba and trombone), it's not easy to play fast passages that involve jumps (notes 2 or more semitones apart).
I would like to know how to transcribe passages like these for low-register instruments, making them playable for musicians with average skills.