Bob, I don't own a Class A (yet anyway) but have owned two Ford V10s and rented many more RVs with them for long trips with family, and every one of them was loud, particularly at high RPMs.
My present van is so light that it practically never shifts out of overdrive at highway speeds, so the noise isn't bad. At 75 MPH we can carry on a normal conversation. And if it shifts to drive, it's loud but tolerable.
However, one time I stepped on it hard in heavy traffic to change lanes at around 45 MPH, and when it downshifted it went from OD to second and it was so loud that it startled me. And that's in a van with factory doghouse and sound insulation.
Above 3500 RPMs it starts to get noisy, and above 4,000 it's too loud for me. That's one reason I'm looking forward to see how much of an improvement the new V8 can make. That an improved fuel economy.
For what it's worth, I once rented a Ford Pickup with 4.6L Triton V8 and it too was loud at higher RPMs. Maybe it's just part of that engine family.