[prndl]

The factory Onan sits in the front area Yes. But. When they install it they cut out the floor (see the slots in there now) and the Onan blows the exhaust cooling air down from the bottom of the generator. Honda, not so much.
If you are generator prepped you should be able to install a male 30amp plug to the installed wires in the front compartment. Then run your extension from the generator in the truck bed to that plug. You could also make a male plug like on your power cord connection on the front compartment wall.