Charging system and other wiring change help needed

The thing^^ I don't care about with that disconnect is you STILL have a hot wire all the way back to the alternator. If you buy a good quality 4 post (2 pole) disconnect, which are now readily available, you don't need to do that.

Fuse link vs fuse, your choice. Thanks to the stereo industry, there's a good selection of high amp fuses available.

If you do go "one wire" you need to way oversize the charge line. This is because the charge wire is ALSO the voltage sensing, and any drop on that wire, will cause the system to run "low"

I really don't care for "one wire" setups. If you use a regulator with typical 3 wire setup, you can "kill" that excitation wire with your disconnect, and that will kill the engine.