I've searched through the code but can't find any defines for changing the current sense amplifier output offset voltage. The DRV8302 current sense amplifiers have a linear output range starting at 0.3V, so it would make sense to offset the output at 1.80V instead of 1.65V. The easiest way to do this on the DRV8302 is to use a voltage divider off the 5V supply because of the DRV8302 internal voltage divider resistors, BUT there don't seem to be any software defines that configure this voltage. Is this hardcoded or is it calculated from Vreg which is hardcoded to 3.3V for most firmware?
The alternative is to reduce the positive linear current sense range, which isn't terrible but isn't optimal. Maybe no one is using the older V4 hardware but it's still more cost effective than V6.