Finally figured out a workable solution.

I wiped the 100mb Win7 system partition, & replaced it up with grub4dos. grub4dos does the same job as the Win7 boot menu - but it can be written in a way that doesn't require any user interaction:

#Don't show this menu to the user
timeout 0

#First try to load the encrypted OS.  If that fails...
default 0

#...Fallback on the unencrypted
fallback 1

#Main OS
title 1
root (hd0,1)
chainloader /bootmgr

#Decoy OS
title 2
root (hd0,2)
chainloader /bootmgr

So what happens is, the VeraCrypt bootloader appears. Whether you type your password or press ESC, it will load the grub menu & try to boot the encrypted OS.

->If you actually typed your password, the encrypted OS will be available and will successfully boot. ->If you pressed ESC, the encrypted OS fail to boot and fallback on the unencrypted.

So to the user, everything is invisible & automatic, and it essentially behaves the same as the two hard-drive situation :)

Finally figured out a workable solution.

I wiped the 100mb Win7 system partition, & replaced it up with grub4dos. grub4dos does the same job as the Win7 boot menu - but it can be written in a way that doesn't require any user interaction:

#Don't show this menu to the user
timeout 0

#First try to load the encrypted OS.  If that fails...
default 0

#...Fallback on the unencrypted
fallback 1

#Main OS
title 1
root (hd0,1)
chainloader /bootmgr

#Decoy OS
title 2
root (hd0,2)
chainloader /bootmgr

So what happens is, the VeraCrypt bootloader appears. Whether you type your password or press ESC, it will load the grub menu & try to boot the encrypted OS.

*If you typed your password, the encrypted OS will be available and will successfully boot.

*If you pressed ESC, the encrypted OS will fail to boot and grub will fallback on the unencrypted.

So to the user, everything is invisible & automatic, and it essentially behaves the same as the two-disk situation :)