I'm wondering if this looks right:
This is the layout of a windows 10 installation on a separate drive:
It is started with this entry from grub (on another drive):
menuentry 'Windows Boot Manager (on /dev/sdc2)' --class windows --class os $menuentry_id_option 'osprober-
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd2,gpt2 --hint-efi=hd2,gpt2 --hint-baremetal=ahci2,gpt2 XXXX-XXXX
search --no-floppy --fs-uuid --set=root XXXX-XXXX
It was installed as the only drive in the system. All other drives were disconnected so it the installation process could not mess with it. Once the installation was done, i connected the rest of the drives and with this os-prober thing, it automatically found the windows installation.
The tiny partition you are not able to access seems to be present here too; this is what i meant in an earlier post, when i mentioned that the windows installer messes with the drives in some obscure microsoft way...
Once windows had all the needed drivers installed, i made an image of the whole disk with dd. So every time it breaks, i can just roll back to that state. Any other disk imager works as long as you can verify the result and make sure you're able to use it in case of a total loss of installation.
However, even with all the careful planning, windows sometimes manages to kill the grub on the boot drive. No idea if this is just a normal ms fuckup or if they do this in spite... I then have to boot a live linux and tell grub to reinstall itself.
Anyway, i'm sorry that all this doesn't help you now but at least you can make it less painful in the future.