Well good news, I found the culprit.
I troubleshot this way.
1. Tripped the breaker for the power converter, whine still present.
2. Repowered the converter then pulled the fuse for the fridge/heater. Whine was gone. Noticed the LP detector light went off as well. Replaced the fuse and whine returned and the LP detector was repowered. LP detector is powered on same circuit as fridge and heater.
3. Pulled the LP detector out and noticed it had its own 3A fuse. Put the LP detector right next to my ear and determined that was where the noise came from. Pulled the 3A fuse and whine gone and the LP detector was powered down
The RV has a Safe T Alert (model 35-742) LP/CO detector. Further research has shown the whine is inherent with this model. Others have had the same issue.