Dual boot with separate drives

Some BIOS/UEFI systems have a Boot Order Lock. You can configure to your liking and then lock it.

That said, Windows won't touch the separate Linux drive 99.9% of the time.

Install Windows drive.

Create one 512MiB fat32 partition, set boot and ESP flags, and then a second NTFS partition in the remaining space with GParted. (This will "force" Windows to not create any silly recovery partitions).

Create your Windows install media keeping in mind that the usual methods no longer work due to the 4GB file size limit issue.

Shutdown and disconnect Linux drive.

Boot to Windows installer and install to Windows drive. (Selecting the main partition as the target when prompted. Windows installer should see the boot partition and configure on its own).

Disable Fast Startup in Windows.

Connect Linux drive and change boot order in BIOS/UEFI to boot to it.

Run sudo os-prober, sudo update-grub and reboot.

Profit.

/r/linux4noobs Thread