@Lundy Along the lines of what 2Pbfeet is suggesting...
Down at our shop & horse barn we have a
down hole well pump that fills an above ground storage tank in conjunction with an
above ground jet pump that pumps a pressure tank to 60 psi.
Before we had
a well problem, the well pump pressurized the pressure tank randomly as required. However, now due to a barn well issue the well pump is on a "pool timer" that is set to only activate a few minutes at different intervals 24/7 to replenish
1500 gallon above ground storage tank as required (
long story why this is needed due to a restricted well issue not allowing long duration well pumping).
Well pump timer only activates if the 1500 gal holding tank's low water "on float" drops in the holding tank by a foot or so due to water consumption. It also has a low water "off float" tank float to stop jet pump if holding tank were to run nearly dry. In your situation... assuming you don't have a restricted well & have sufficient water resource you might only have to run your 3-phase well pump off your generator once or twice a day to fill a large holding tank sized to your needs.
In our situation, if well pump timer is on & holding tank float indicates a need for water, it energizes the well pump which is timed via the pool timer
until the high-level float #2 cuts it off or pool timer run duration shuts it off. It will repeat this process as well timer & tank water level requires on a 24/7 basis in our case while on utility power.
So, in your case perhaps you could dedicate 1 genset to always run in 3-phase just for the well pump to completely fill a
x-gallon above ground storage tank once or more a day depending on your typical daily needs. Much more efficient & better for the genset to
run your generator longer intervals to fill a storage tank, than multiple start/stops due to triggering it off your pressure tank switch.
You would need a separate 120 or 220-volt "jet pump" that utilizes the stored well water piped to it
from a holding tank & it would only come on when pressure tank PSI drops to a pump-on set point taking that burden off your well pump. In our case, the water line pressure tank's switch is set to come on at 30 psi & the jet pump runs up pressure tank to 60 psi & then shuts off. Given our situation, just the jet pump is available 24/7 to maintain water line pressure since it has ~1500 gallons well water to draw from stored in our above ground holding tank.
Anyway, just some food for thought...