After researching this for years - and struggling as Prof and sound guy are - I too don't want to hear the generator at all. The best solution I've seen thus far is Soundguy's design.
It's light weight, small, effective and ease to transport (though it doesn't lie flat like prof is looking for).
Someone on hear years ago pointed out that sound waves that are blocked from reaching you reduce the footprint - and I tried to emulate by using thinner pieces of plywood - leaving the top open for circulation.
It worked at home - but when I was camping, the leaves of the trees reflected the sound back down.
You could take what Soundguy did for a template, use hinges to hold things together and put quick release pins in the hinges and possibly get what you're looking for.
The most important thing is airflow - and again - look at what Soundguy has done for his 2000 and see how he's allowed the built in fans to pull the air in and out without impeding the airflow.
