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I'd suggest it isn't just the voltage that's to be looked at. For instance, the Delcotron's will *only* put out 14.3-14.4 volts, no matter what the battery voltage is. There are other alternators that work the same way, using pulse width modulated DC and only putting out 14.4 volts and varying the "number of zaps per second" that they give the battery. So while the alternator is running, a simple voltmeter may only see 14.4 regardless of battery voltage.
IIRC a conventional car alternator cuts down to about 10% of full output within 15 minutes, so running it for an extra hour might mean you have run it for 3x-4x as long as you could have run it, with a real regulator applying full output for a much shorter period. I'd go for external regulation, or at least find out for sure how your Bosches were making decisions, and perhaps just install a manual override so you could get full charging from them. (i.e. fool the sensing wire, and in the alternator outputs are combined, make sure there's just one sensing wire controlling them both.)