After reading some more on the Caswell LCD manual, I bought a little chinese 5A lab supply with current and voltage limiting. After using my bath a few times, I found the required voltage to be relatively low (sometimes under 10 volts) for low current runs (3-4 A/sq ft.). I haven't noticed the need to limit the voltage yet, but I can see how limiting the voltage in a 12 A/sq. ft. (average) run could make a difference.
I've been working around 6A/sq. ft for about 2 hours, which fits the 720 rule but is longer than what I think the Caswell manual describes. It seems a bit contradictory in places. The dye penetration has been much better with the lower current densities, compared to running 13 volts for a time to match whatever current I would get.