My toy hauler did not have a transfer switch. The genset had a female plug where you connected the shore power cord. You could do the same if you have shore power input in a storage compartment by mounting your genset output to this location.
It allowed my hauler to be plugged into a pedestal or the generator without being able to plug in both at the same time, so it was dummy proofed. I liked having my 2 phase Onan 5500 available to exclusively power the hauler, house, welder or large air compressor without needing to wire isolation or additional circuits.