Alde 3020 on propane

You could try adding some sound damping panels under the bed, above the Alde.  I didn’t notice any loud noise or thumping that was enough to wake be up.  That said, you can get sound panels designed for inboard diesel engines used on sailboats from a marine supply.  They are heat and flash fire proof also.  Would offer additional protection for the bed — hum, think I will look into this also... 
cheers

@RCB, what is your elevation? If you are over 3000’, you would need to select the high elevation option on your Alde control panel. That could be the thumping noise.  My 400 would sometimes have the thump at 2000’.

I have had the same loud sound when running on propane that's even audible outside the trailer. The sound does not happen on electric power. I noticed that the exhaust cover on the outside seems to be sooted after propane use. BUT I didn't realize there was an altitude selection on the Aldi control panel. Will be checking on that now (my elevation is 4900 feet and only goes up🤔)

@Samrollseyes - The Alde 3020 with the high altitude selection came out in the late 2018 models starting with the Dec. 2017 builds.  Go into the Tool menu and look for the “mountains” icon.

I think nuCamp came out with a High Altitude kit for the 3010, you could contact customers service as see what is available.
cheers

@Samrollseyes - we had the factory install the high altitude fix on our 2017.  Tested it in Utah at at least 6,000 feet and it worked well.  No problems at sea level either and you don’t have to change any settings.  Once and done.

Yeah @RCB, many have had noise problems with the Alde due to high altitude. Yours might be a different noise than the rumble that they're referring to. Good luck!