Denny, I am thinking you may be referring to the Honda i2000?
I modified an aluminum, underbody box from TSC to fit. I based these mods on photos from a company that makes small genset boxes for truckers, etc..
You can see the photos of my completed and mounted box in the Tom-a-Hawk photo album under genset box sub album.
I cut a much larger exhaust end flap than the commercial manufacturer uses so that end of the genset almost protrudes out of the side. I have used this setup for many hours with no problems. I also put low set ventilation screens on the forward side of the box to eliminate any fuel vapors. I did not put any flap openings on the aft side to avoid direct water intrusion from waves. I did drill some 3/8 inch drain holes in the bottom aft corners.
The box is mounted to the swim step with four 3/8" SS bolts and a rubber base pad. Fiber pads were placed on the sides to avoid aluminum/plastic rubbing. Wood blocks placed on the floor to stabilize genset position.
The cooling fan pulls air from the control/intake side and blows it out thru the exhaust end. The large aluminum exhaust flap helps to deflect exhaust from the engine control cables, etc..
On the control side are three small aluminum flaps: 1- for shorepower line hookup alone 1- for switch and control 1- access to control panel bottom connections/switches.
The optional yoke for tying two i2000 Honda gensets together is used since it provides a handy, 30 amp, locking receptacle that fits the marine shorepower cords we use.
While you could hook up a normal household type 15 amp, two prong w/ground plug-in to the genset, that would be a weak connection and the length of the necessary adapter is the same as the lengh of the Honda 30 amp yoke adapter.
'Hope this helps,
John