Yamaha Portable Generators and B class
I have a couple of Yamaha portable generators - the 2000 watt and the 1000 watt units. I had bought the larger one first for my tag-along, but found out it would not run the 13500 btu AC on it. The small unit I had bought for use on my boat. It's a handy size. Both are very efficient and extremely quiet.
Just for grins, I decided today to try to hook up my Travato to the 2000 watt unit and see if I could run the AC. Much to my amusement, it did! I could run the 13,500 btu AC on max cool no problem. It also would run in ECO mode and would ramp up with the AC coming on. The battery charge/converter, fridge on AC and lights were all on too.
Is it quieter than the on-board Onan? Not by much I'm afraid. The yamaha is running flat out, so it's not so quiet. Without a db meter I can't tell you exactly the difference. It isn't as "clattery" or harsh sounding that is for sure. You also have some directional control as to pointing the sound with the portable.
Not too long before I got my van, I had purchased a Honda 3000 to use with the tag-along. It's the king of quiet generators and could handle the AC without any fuss. I was going to just mount it in the back of my Silverado. Too big/heavy to carry in the van, so it has a home in the corner of my garage in case the power goes out.