I understand, I came from a truck camper and found the noise was a lot more in the C.
My biggest issue on the day I picked it up was that the big window behind the driver was slightly open and the noise was HORRIBLE!!!!!! I was almost in tears as I knew I could never stand all that noise. After I got out of town I stopped to do a check of the unit and open and closed everything and that was when I found the window. It looked closed but was not, a couple minutes of adjusting and it was SOOOOO much better.
One of my mods was to add carpet and underlay for warmth and comfort and as soon as that was done the noise level dropped big time. Still not perfect but a lot better, absorbs road noise and if there is noise in the camper dulls that.

The next step was to adjust things. I found the stove cover was rattling so placed a dish towel under that. Pots and pans were rattling so added those sticky foamy shelf liners to stop the lids from rattling. The blind was rattling so made sure to put that up in the morning to stop rattles. Side door needed an adjustment to reduce wind noise - was not bad but you could hear some.
Now it is a lot better, almost one hundred percent quite from the back end, still some road, wind noise but after all look at the size of what we are driving!