Just a quick update in case someone else might benefit from this info down the road. I ended up returning the Dave Brown spinner. I called Tru Turn and explained the setup. They recommended their "Ultimate" style spinner which is longer/deeper and they believe would accommodate my setup. They also recommended their "wide mouth" version of this spinner which has slots that will accommodate the APC props I want to run without custom slotting. Lastly, they told me the spinner and adapter nut would be returnable if it didn't fit. $51 total ($10 shipping).
Thanks,
Matt