Deck Box as a Generator Quiet Box?

I had a Champion 3500/4000 watt since 2012 and a Work and Play 30 foot toy hauling trailer that I pull with a F250. Here's what I've found, the generator is listed as 68 decibels, the muffler is pretty good, but about half of the noise actually is just mechanical engine noises. I put the generator in the bed of the truck, on a heavy piece of carpet, have a six inch fan that claps on to the generators frame and is plugged into one of the 115 outlet blowing air on to the generator's engine cylinder head, then I have a three foot, 90 degree exhaust pipe extension that routes the exhaust up and out of the bed of the truck. A tonneau covers the entire truck bed, I just open the tailgate, clip on the exhaust pipe extension, open the fuel valve, plug in the 30 amp cord and hit the starter button. Wait a few minutes then close the breakers inside the trailer. The 30 amp cord is long enough to reach the trailer's power receptacle, I also have an extension 30 amp cord if I want to move the truck further away from the trailer. With the generator sitting on heavy carpet, a tonneau cover covering the generator, a fan blowing air on the engine for extra cooling, with just the tail gate open, I can run it even if it raining. The noise isn't that bad, no worse than sitting next to a semi truck idling next to you all night long at a truck stop or a Walmart.
We only use the generator when we're parked out by ourselves in remote areas.

P.S. The generator only cost $249.