I think I figured out my coal issue...last couple days I been pushing the big hot coals over to the right so I can get down to the powder on the bottom of the left side, then push the top layer back over to the left and get the powder out of the bottom of the right side, then even the coals back out. I still get to keep the fresh hot coals and gain room in the stove. Dump the hot stuff in the firepit outside and worry about it in the spring, which the last couple years in central Ohio spring starts in February.
Yep, your strategy of moving the coals around to remove ash when it has burned down a bit is good. There's plenty of heat value in the coals and they radiate plenty so you want to keep them in there but unless it is really hot they don't burn down fully themselves. Depends a bit on the species of wood I'm putting in there but if I load it fully every time the coals will accumulate to a significant extent. So now and then I'll rake the coals forward a bit (the air movement in my heater is down the front glass then towards the back then up and then towards the front - so stuff at the front burns fastest) and put a couple of small pieces in that burn faster and keep sucking plenty of air in - that helps the coals burn down well so you're maximising your heat out of your wood.