I do certain "summertime" tweaks to my system, for similar reasons, too. Coincidentally I have an "opportunity" diversion load, heating water troughs for horses, but that is only used in the winter of course.
I don't think there is a hard limit or threshold on charge current, whether you're referring to bulk, absorb, or equalize, but you can tell that having more is always better and offers choices. A lot of things affect what % is acceptable, especially the amount you draw it down every day.
In my case, the very reason that I bought solar panels at all was because of the big battery bank I inherited, and I didn't want to starve them. Those PV panels have pulled the bank up to float every day whether the wind blew or not. Admittedly I don't draw them down much, especially in the summer.
In your case, I think you'll be able to see if the batteries are being starved, by noting the time of day that the Classic goes from bulk to absorb or float phase. Have you been logging data (either in the digital way, or the pen+paper way)? This would give you a pretty strong indication of how robust the daily charges are. If you can say something like "Last year in August on a sunny day the bulk charge lasted 2 hours and today it's sunny but the bulk charge goes until noon" then you know you have a lack of PV+wind for the size of the bank.
That's actually the focus of my system logging now: battery health (voltage/charge/temperature). I don't bother logging all that other WT performance and wind speed and blade RPM any more. I just want my batteries to last a long time.
If I had the money and the time I would have upgraded to a Midnight classic years ago. I've been aching to take advantage of all of those features rather than manage my hodge-podge of gadgets.