Thanks for your advice Ralph (again!) I will try your suggestions next run. I also would prefer the RD use natural air to maintain the temperature but was so happy to get a 10+ hour cook at this temp/setup.
I wanted to post this video of my setup with Ralph's Rotodamper and of course Bryan's HeaterMeter 4.2 setups. I use a Char-Griller Akorn and had the top damper almost completely closed on this cook. My settings were some I found on this thread as my own attempts had been extremely erratic until...