"Jose" wrote

5: Tape a microphone near the speaker, and monitor the audio with the speaker
(as well as the headphone). By putting the mic in different positions, you
can choose the balance you want. Run the mic directly into the camera's audio
input.

That sounds like the best, and least expensive idea. With a spare headset and a
little thin foam rubber, you could put the camcorder mike inside one earcup,
than put one wrap of foam around it. Experiment , and add more wraps as needed
to muffle the engine noise.
--
Jim in NC