Google Drive on 3rd Partition with Windows 7 and Bootcamp
It can be done.  I have two Macbooks setup like this.  Partition 1 is Mac, 2 is Google Drive, 3 is Windows.  All can be seen, written and read from both OSX and Windows.

To do this, run bootcamp assistant and partition the drive so that the Mac OS partition is the size you want the OSX + Google Drive to be.

Do not install Windows yet.  Reboot into OSX, then go to disk utility, and partition the OSX partition again, this time call the second partition as Google Drive. You will now have 2 OS partitions, and one NTFS.

Now reboot, and hold down alt to choose to boot from your windows installation media.

Choose advanced installation, and select the partition that you want to install Windows on to. You may need to choose to format the partition too.

Windows will install.

Now reboot into OSX, setup Google Drive and choose advanced.  It will ask you to choose where Drive is located.  Here's the tricky part..... if you choose the new partition, it will say it's not empty.  So you need to show hidden files (there's many tutorials and methods on line to show how to do this).  Now you need to delete these 4 files.  Each time I've done this has been trial and error.  Programs like BlueHarvest may help, but you will need to use Terminal and various delete commands to get them to go and do in the correct order. It took me about 45 minuets last time.  I lost track of the correct order.  When they all do delete, have the Google Drive setup assistant ready to choose the now empty partition. Select the drive and  it will start to sync and you're done.

I use Paragon and Mac Drive 9 to allow full read / write from both OS.  

Mac and Google partitions are Mac OS Extended (Journaled) and Windows is NTFS.