...Could a guy build a insulated square box that goes over it and cut hole for exhaust? would that work or kind of stupid?...
Like other people have said it is difficult. Generators need to get rid of heat and exhaust, so building a container that meets those requirements and is portable is difficult...not stupid...but difficult...oh, and I should add not easy either.
The superquiets (maybe we should just say "quiet") have had a lot done to them to cut down on all the internal mechanical noise. There is a lot more to that than adding a bigger muffler and putting a blanket over the generator to absorb the noise.
Also these types of gensets tend to be more fuel frugal when running lower than full power load.
Still you need to determine not just how much power you need, but how often, where you will use it.
If you are going to use it in a noise rich environment (like at NASCAR event) quiet genset may be less important; or maybe just to top off your batteries. In situations like that, the contractor type genset, which is far cheaper may serve quite well.
If noise levels are a concern gensets like Honda, Yamaha, and maybe the Boily may be a better purchase. They are better on fuel and provide cleaner power.
A lot of people really like the dual Honda concept for the same reason passenger aircraft frequently have two powerplant...engines turn or passengers swim. One can fail and you still have some power. Additionally, in the cooler months, most people can get by with just one of 2KW generators. Other times you may need to use one at home and another for some other activity elsewhere and that is rather hard to do with one generator.