Honda eu series are in fact inverters
that take the produced DC current and change it to AC. Honda does make a paralleling kit to allow you to hook up two generators. I don't see a problem in hooking up one generator and a separate inverter with one of these kits. Such a setup may be adequate to start the unit at startup and as it cycles. Having said that I would not consider it a practical option to power an AC unit on a boat as the inverter will share the load and will be continiously drawing juice from the batteries that power it. You could parallel two Honda generators for a 4,000 watts output but now we are talking an additional 50# and $1,000. Depending on the usage you intend to give the unit on the hook there may very well be a much simpler solution; Purchase a 5,100 btu window unit from Sam's Club for around $80 with a mechanical switch and it will surely be powered by the eu2000. If for a few nights a year you can put up with the inconvenience of setting the a/c up in the companionway you can surely sleep in comfort. The reason I recommend the one from sam's is that it is the smallest unit I have seen.