The solution is to use a transfer switch with in-phase transfer capability.
My Thomson switch waits for the generator and utility to be in-phase with each other before transferring the load.
This allows transfers back to utility without the equipment even noticing, as well as seamless exercise under load.
Often I don't even know the utility has returned until I open the back door to see if the generator is still running.
What model is the Thompson? I'd like to look up the specs for the next one thanks