I have the same problem with my C-60 which has the dumpload also.
But with mine it only trips the inverter (Small Xantrex 600W rated/1200 surge) when the batts are fully charged with no load on the inverter at the particular time the mill is at maximum (say around 100watts+ or so).
It will also trip sometimes with only one 20watt load on it.
I suspect the problem is I am only charging two golf cart batteries at a time. (only 220 amp hours total).
I am still learning myself, but was wondering if it would trip the inverter if I was charging a BIGGER battery bank like 500AH or more??
I can't imagine everyone else having this problem esp/w a whole house set-up. I only have a small system right now.
I actually have to charge two sets of batteries seperately since one set is older and less voltage after final charge. I Hook the two sets together at night to watch hours of TV and then disconnect the two sets so I don't sulfate the new batts over time from the old ones dragging them down all the time.
Could probably get a voltage regulator on the mill I guess??