Utility power comes in on 3-wire and you split that to 4-wire at the entrance panel, and ground the bonding point where it splits. Maybe the same can be done with the generator. 3-wire from the generator, a 3-wire inlet, and bond it all in there so 4-wires go to the transfer switch. Still gotta switch the neutral.
In a better life, I'd have a big 100+ kVA, and the transfer switch would (or maybe could be) be the entrance panel (if it can also be the main cutoff). Now the bonding would be in the transfer switch, eliminating one issue.
