Using Easy2Boot you can boot from partition image files. This means you can have a single USB multiboot drive and boot almost any image via UEFI or MBR booting. Secure UEFI boot is also supported.
A .imgPTN file is a complete binary copy of a whole partition. When you select a .imgPTN file, the current Easy2Boot partition will be replaced by the .imgPTN file. This means that the contents of the USB drive will then be replaced by the contents of the .imgPTN file. See http://www.easy2boot.com/add-payload-...
Your USB drive can contain many .imgPTN files - Windows Install images, Linux LiveCD images, MSDaRT images, KonBoot, Rufus USB drive images, etc. and you can boot from any one of them in normal MBR mode or UEFI mode.
Using Clover, you can UEFI boot directly from the grub4dos CSM menu (via Clover menu entry) without needing to reboot the system and boot via UEFI to the USB drive!
Note: If you make .imgPTN files from Windows 7/8/10 Installer ISOs, then a 'Helper' USB flash drive is no longer required. You can thus use just a single USB HDD to install a large variety of Windows Installs.