If the rig is destined to be a power pole princess, then 99.99% of the advice given for serious engine alternator charging (upgrades) can be ignored. Late 80's converters were battery boilers. If the converter is a bright brushed aluminum box about the size of a loaf of bread with large red & white wires sticking out of one end and has a fan on the other, let me know -PM- if the owner wishes to upgrade.
Easier than watching pretty, colored, monitor lights on a power pole princess, switch on a light, if no light, problem. Both are useless for battery monitoring.