My recommended method - Use BootChamp (NOT Bootcamp) with SIP disabled.
Other possible methods
1) Use system preference to select Windows partition on next boot. Then perform a PRAM reset to go back to MacOS.
2) Install HS on a HFS+ partition, so that you can select it for the next boot in Windows Bootcamp apps
3) Install a 10.12.6 at somewhere, so that you can select it in Windows bootcamp apps, then further select HS inside Sierra.