Big Hard Drive, what's the consensus about partitioning?

Yes, junctions are like symbolic links, and those I have gotten to work in the past.

It's mount points that I have been unable to replicate in the Windows environment.

Well, I just did it now, and it works fine. Go into Disk Management, find the volume you want to mount, right click, and choose Change Volume Letter and Paths. This will bring up a dialog that shows you any drive letters or paths that are already assigned. Typically, it will have something like D: assigned already. Remove the existing letter if you want (note that you cannot remove the letter from a volume that is being used for a pagefile), and then click Add. Browse to an empty folder, click OK a couple of times, and voila, your drive is wherever you told it to be. You can have it on both a drive letter and a path at the same time, if you wish.

The icon changes when you do that, so I'm suspicious it may actually use a junction point to aim at the drive letter, or maybe at the hidden system mount point that you don't normally see (they're super complex, so they're normally hidden). So I don't know if it's REALLY a mount point, or if it's just faking one, but it does seem to work just fine. And Explorer calls the directory a mounted disk if you bring up Properties.