I can't tell you about the champion but I have a 3000 Honda with remote start bolted at the front of my truck bed. The first year of using it I didn't have solar so I ran it for all my charging while boondocking.
I built a ventilated metal cabinet out of 12 gauge steel with a hinged top and a vent at the top drivers side and a 10 inch 120 volt axial fan at the passenger side. I usually opened the lid at a 45 angle or so but often ran with it closed. A few times people asked me how I was doing it because they never heard the Genny. We always had lights on, 40 inch television, satellite etc.
I had the 12 gauge sheared to size and welded everything myself. The fan was pricey so the whole thing cost about $200.
Now that I have a lot of solar I removed it for weight saving. Even without the cabinet when I park the truck with the hood to the pinbox we forget that it's running. I routed a 10 cable with twist lock that is about 25 ft long from the transfer switch out under the bedroom overhang past the pinbox.
Depending on how and where you use it you might try a few other tricks like foam shielding etc.
Somewhat involvedEasier
