Lavalier Mic Recording in Car - Any Tips?

I’m recording myself and another person, just voice, in a car while driving, using lavalier mics. I’m not so concerned with road noise as I am with capturing a good, clear, strong vocal. Right now, I have the mics clipped at right above the sternum, center of chest.

The issue I’m experiencing is that the loudness of the vocals varies quite a bit, so that on the resulting recording, quieter parts are far too quiet, while there are loud spikes that create clipping unless I lower the input gain – which makes the quiet parts even less audible.

I’ve messed around with compression, but everything I’m doing right now results in a distorted sound.

Is there anything I can do, including better mic placement, optimal compression settings, other filters/effects, etc., that can improve the quality of my recordings? Again, road noise I’m not so concerned about, but I would like the vocals to sound clear and full, without distortion or that heavily processed quality.

Thanks for any help!

Headset microphones would probably give you better results in a car than lavalier mics. Is that an option?