Hi Dane, also saw your video on Vosk's channel and very impressed.
I know you addressed building bank with your power company, and I have a similar arrangement (but much smaller one) using Solar City that came with the house when I purchased it -- but I have been recently interested in the idea of building a powerwall.
As stated, batteries are quite expensive - to run 15 cards drawing 200w each, I would need 10,000 cells, and you are lucky to get those at a dollar a cell plus panels to charge them.
Would you ever consider this ? Sounds like you have a fine plan as it is, but if the grid goes down (which it rarely does) you have only that generator. Thoughts?