The advantage of the fancy electronic regulators (other than much better regulation) is they usually have "soft start" which brings the alternator on line over 15 or 30 seconds. I've never tried just switching the field current, could lead to some transients? On the other hand, that is just the way the old make-and-break regulators used to work, so maybe there wouldn't be any problems.

I usually charge in the morning (if I am needing to), the alternator has enough to feed 200 amps to the batteries while running the refer/freezer compressor and water maker. With those jobs done there might be another 30 AH to put back, but it will necessarily be at a low rate so I let the solar take over. That worked pretty well in the Bahamas. When down, the AGMs would recover about 3 AH per minute, so it didn't take all that long to get them up to 80 or 90%, then it slows down so they get the solar the rest of the day.