When dealing with efi, I shrink the c-drive partition, make a 500mb /boot partition, and make the last partition usually a luks encrypted volume, or a lvm pv directly if no encryption desired. I still like to keep /boot and $else separate.
Last time doing this with win10, I assigned 60gb because I only really boot it for bios/thunderbolt dock updates. Installing and using a win10 vm minimally, orfice365, visio, other stupid windoze-only things, and os/orfice updates, I'm backing up to around ~50gb of disk so far in that. If you intend to do more than use it use it for bios updates, I'd suggest more than 60gb of space. Win10 is a pig.
I miss the old days of running xp with everything on a 6gb disk image...
/sda1 == /boot/EFI
/sda2 == /media/windoze-cdrive
/sda3 == /boot
/sda4 == (encrypted) luks-vol0
/dev/mapper/luks-vol0 == pv0/vg0
/dev/mapper/vg0-root == /root
... etc
-mb