Very good pictures - you make having an opinion easy.

First - I don't think there are any residual pools of water in the block that haven't been reached with your flush and fill technique. But, even if there are - over time the 50/50 mix will still ooze its way into those residual pools and once it does, the protection is still going to be pretty good.

Just to be extra double sure, in a week go back, do one more flush and check the protection point. It will probably be around -30.

This has been a bit of a pain, but now when it gets really cold some night, you won't lay awake and wonder "Is that engine going to freeze up tonight??"