After building and using the battery pack for a little while, I started to think of some improvements.
For example, the switch I installed has an ampere rating close to the maximum expected amperage of the load. Rather than a bigger switch, I added a 60A solid state relay, controlled by the existing switch. The switch now only needs to carry a few milliamps.
I also wired it so this relay turns everything off except for the charge input.
I noted, however, that the BMS itself imposes a small load on the cells, even when it is not in use. I suspect that it will deplete the cells over a period of time.
And last, I added a 30A resettable breaker on the battery positive side. You know, just in case. I consider it a check valve for the magic smoke…