Thanks for the responses so far!
I was going to post a separate post about how to best burn the coal, because while I don't mind the work, it seemed like a lot to deal with. What I've noticed is that if I'm adding coal every 12 hours, i.e. when the coal in there is burning hot, but close to the end of the burn, I have a real hard time getting the fresh coal to start. I experimented a bit and while I can always get some of the coal going, I never seem to be able to get it all going. A pocket goes out and that pocket will never relight, it seems. Is it possible I'm not getting enough oxygen in? What I did learn is to not poke the coal, as that will put it out very quickly, I suppose because nut coal is so large. BTW - the furnace does have shaker grates. When I shake, I typically shake until just a few small red specs start to fall. Should I shake more -- i.e. until larger coals that are still burning start to fall?
Back to the original question, I suppose that with proper maintenance of the motor and blower and all related parts, and with the inverter backup, there's nothing else to really do to be more careful with this setup?
Specifically to DavidL's question, CapeCoaler gave a good link. That's not specifically the inverter that I have, but the same premise. I have a bank of 4 large AGM batteries in parallel that will give a good 12 hours or so runtime on the motor should a major problem occur -- more than enough time to drop the fire if I had to. My inverter doesn't have a built-in charger, and so I have a separate charger that does a smart charge and maintains a top-off charge when the batteries are full to maximize battery life and performance. The way my setup is, the inverter just passes "shore" power, as it's called, when it exists. If I lose power, it switches right over to the batteries (which otherwise are sitting idle and ready).