If there ends up being a way around the 240V requirement, and you can use 120V, Honda makes an 'add on' 2200 watt model called the Companion, which can work all by itself, or, using a simple set of parallel cables, connect to your current Honda genny. The Companion has a beefy 30A twist-lock receptacle, so you can pull the full amount of (4.4kW) power from *both* units via a single receptacle on the Companion.
This makes it super easy to then plug into a an inlet box to supply power to a transfer switch.
There are also a number of third-party external tanks that can tee into the fuel caps of both generators, significantly increasing the run time. FYI, the Honda EU2200 and Companion 2200 both use fuel pumps, so the extended-run tanks work nicely.