I am into 8+ years full time RV and noise from the AC was not bad on moderate days, only 90+ when I had to run both units but the energy used was huge. I installed a small window unit Evap cooler, into a wall and setup for easy removal for the winter. It uses almost exactly 20% of the energy, low enough to run on solar when I finish that project(very DIY)
So, I run the Evap most of the time as needed seasonally and run the AC unit on the other end of the RV, shared and ducted, when listening warrants paying attention or just get a bit hot to have almost no background noise. Then again I just want to get a buzz and really crank it up and dance with the wonderful woman that blesses me with her presence.
Rick