The default actually works pretty well these days.
Messing with the EFI partition, for instance by attempting to have two of those on separate disks, will probably cause you more pain than Windows will. As far as I understand, only one EFI partition can be configured in BIOS as the boot partition, so you will have to change the configuration in BIOS whenever you want to boot to the other OS.
Windows does have a history of changing the default EFI bootloader once in a while; however your chosen bootloader is still there, just not marked as the default anymore. A Windows app like EasyUEFI will let you change the default back.